Added multiple options to webemulator. (X16Community#308)

* Added multiple options to webemulator.
Now the webemulator is able to handle the following options:
* ram = amount of memory in steps of 8K (8-2048)
* cpu = c816 or c02
* mhz = speed in MHz, minimum 1
* keymap = same list of keymaps supported as normal emualtor
* longpwron = Boot emulator into RAM diagnostics
* widescreen = enable widescreen if true
* capture = capture keyboard and mouse if true
All of the above options are available on the address/url or in the manifest file.
On the address line longpwron, widescreen & capture do not need values to be enabled.
In the manifest file, they must be set to true.
Options in manifest file take precedens over options on address line.

* First attempt at documenting WebEmulator options

* Added midline-effects option
This should address this issue:
X16Community#287

README.md

@@ -187,6 +187,64 @@ The following keys can be used for controlling games:
 |Cursor Right  | RIGHT           |
 
 
+Options for the WebEmulator
+--------
+
+The following options are available for the WebEmulator. With the exception of manifest, they all work exactly the same as in the normal emulator.
+* `manifest`
+* `ram`
+* `cpu`
+* `mhz`
+* `keymap`
+* `longpwron`
+* `widescreen`
+* `capture`
+* `midlineeffects`
+
+#### The Address Line
+`manifest` tells the emulator what should be loaded as a startup program. If the file is a .bas or .prg, the emulator will load it and try to execute it. If the file is a .zip, the WebEmulator will get access to all the files inside that zip-file. When using a zip-file you may add a manifest file to provide additional information - See section below for more information on `manifest.json`
+
+On the Commander X16 forums, a link to the webemulator could look something like this:
+https://cx16forum.org/webemu/x16emu.html?manifest=/forum/download/file.php?id=1218&ram=2048&cpu=c816&mhz=10&keymap=da&widescreen&capture  
+This will load the forum file with id 1218 into the emulator.  
+Give the emulator 2MB of RAM  
+Set the CPU type to 65C816  
+Set the CPU speed at 10 MHz  
+Set the keyboard layout to Danish  
+Show the emulator in widescreen mode  
+Capture the mouse and keyboard input 
+The options `longpwron`, `widescreen`, `capture` & `midlineeffects` do not have any values, it is enough to have them on the address line to enable the feature.
+
+#### The manifest.json File
+If an application requires more than a single file to function, for example graphics or audio assets, it is necessary to package the needed files in a zip file. If there are more than one start file (BAS or PRG) the `manifest.json` file can be used to specify the default start file with `start_prg` or `start_bas` otherwise the WebEmulator will start the .prg or .bas it finds in the zip file.  
+
+Here is an example of the optional `manifest.json` file  
+
+	{
+		"manifest_version": "1.0.0",
+		"name": "My Program",
+		"author": "John Smith",
+		"app_version": "1.0.0",
+		"license": "GPL 3",
+		"ram": "2048",
+		"cpu": "c816",
+		"mhz": "10",
+		"keymap": "da",
+		"widescreen": true,
+		"capture": true,
+		"longpwron": false,
+		"midlineeffects": false,
+		"start_prg": "MYPROG.PRG",
+		"resources": [
+			"MYPROG.PRG",
+			"FILE1.BIN",
+			"FILE2.BIN"
+		]
+	}
+
+If the resources section is present, only files specified will be made available to the WebEmulator.  
+Options set in `manifest.json` will override options on the address line.
+
 Functions while running
 -----------------------
 

webassembly/main.js

@@ -73,19 +73,40 @@ var manifest_link = url.searchParams.get("manifest");
 var ram_val = url.searchParams.get("ram");
 var cpu_val = url.searchParams.get("cpu");
 var mhz_val = url.searchParams.get("mhz");
+var lang_val = url.searchParams.get("keymap");
+var diag = url.searchParams.get("longpwron");
+var wide = url.searchParams.get("widescreen");
+var capture = url.searchParams.get("capture");
+var midline = url.searchParams.get("midlineeffects");
 
 var emuArguments = ['-keymap', lang, '-rtc'];
 
 if (ram_val) {
     emuArguments.push('-ram', ram_val);
 }
 if (cpu_val) {
-    if (cpu_val == 'c816')
+    if (cpu_val == 'c816') {
         emuArguments.push('-c816');
+    }
 }
 if (mhz_val) {
     emuArguments.push('-mhz', mhz_val);
 }
+if (lang_val) {
+    emuArguments.push('-keymap', lang_val);
+}
+if (diag != null) {
+    emuArguments.push('-longpwron');
+}
+if (wide != null) {
+    emuArguments.push('-widescreen');
+}
+if (capture != null) {
+    emuArguments.push('-capture');
+}
+if (midline != null) {
+    emuArguments.push('-midline-effects');
+}
 
 if (manifest_link) {
     openFs();
@@ -310,6 +331,40 @@ function extractManifestFromBuffer(zip) {
                 console.log("Parsed manifest from zip:")
                 console.log(manifestObject);
 
+		if (manifestObject.ram) {
+			console.log('Found RAM amount: '+manifestObject.ram);
+			emuArguments.push('-ram', manifestObject.ram);
+		}
+		if (manifestObject.cpu) {
+			console.log('Found CPU type: '+manifestObject.cpu);
+			if (manifestObject.cpu == 'c816')
+				emuArguments.push('-c816');
+		}
+		if (manifestObject.mhz) {
+			console.log('Found mhz variable: '+manifestObject.mhz);
+			emuArguments.push('-mhz', manifestObject.mhz);
+		}
+		if (manifestObject.keymap) {
+			console.log('Found keymap variable: '+manifestObject.keymap);
+			emuArguments.push('-keymap', manifestObject.keymap);
+		}
+		if (manifestObject.longpwron) {
+			console.log('Found longpwron variable');
+			emuArguments.push('-longpwron');
+		}
+		if (manifestObject.widescreen) {
+			console.log('Found widescreen variable');
+			emuArguments.push('-widescreen');
+		}
+		if (manifestObject.capture) {
+			console.log('Found capture variable');
+			emuArguments.push('-capture');
+		}
+		if (manifestObject.midlineeffects) {
+			console.log('Found midlineeffects variable');
+			emuArguments.push('-midline-effects');
+		}
+
                 const promises = [];
                 if (manifestObject.resources) {
                     console.log('Found resources section in manifest.');