[Feat] DNS Record can be automatically created, without manual record…

… creation in advanced. (#6)

* [Feat] Record auto-creation implementation

If script detects given record name has not been created,
it will automatically POST to cf v4 api to create, then
prompt the user.

Tests should follow.

* [Bug] Minor Typo on function create4RecordIfNotExists

Provide `hostIp` as param for function create4RecordIfNotExists.
Solved.

* [Enhancement] Code Clean-up and Follow google shell style.

Info and error message are both handled by shell functions,
rather than echo everywhere and pipes it to stderr.

Global variables were renamed following STYLE_GUIDELINE.

Function variables were renamed following snake_case.

Other code clean-ups, and guideline following.

* [Bug,Enhancement] Typo causes NULL var

Fix where GLOBAL_VARIABLES' names alterd in `cloudflare-ddns` but
stay the same in `cfddns.sh`, which leads to NULL var.

if statements use `[[]]` instead of `[]`.

* [Bug] Record update will occur when HostIp==RecordIp

fixed.

* [Doc,Enhancement] Function comment & file header updated.

Some variables were declared `readonly` for more development-friendly
design.

Function comment and documentation links updated.

`set -o errexit` added.

* [Bug,Doc] `errexit` results in unexpected exit.

Removal of `set -e`, which is short for `set -o errexit`.

Comment & Documentation updated.

cfddns.sh

@@ -1,26 +1,27 @@
-#!/bin/sh
-
+#!/bin/bash
+#
+# Entrance File and Config File for cloudflare-ddns.
 
 # Import utility function here
 # You `cloudflare-ddns` file ABSOLUTE PATH here!
 . /config/scripts/cloudflare-ddns-edgeos/cloudflare-ddns
 
-########
-# Alter here
-########
+#######################
+# -Config- Alter here #
+#######################
 
 # Access Token generated from Cloudflare API token page
-access_token=""
+CF_ACCESS_TOKEN=""
 
 # Can be seen from your zone page, bottom right Zone id
-zone_identifier=""
+ZONE_IDENTIFIER=""
 
 # You DNS record name, with A subdomain
-record_name=""
+RECORD_NAME=""
 
 
-########
-# Alter stops
-########
+#######################
+# -Config- Stop here  #
+#######################
 
-updateMain
+main