Fix ghosted text / ghsted screen issue (See #167)

- Using the 'bg' command to draw images with transparency does not work as expected
- I'm guessing the 'bg' command copies whatever image you choose to the bg buffer
- The BG buffer is redrawn every now and then
- If you put a transparent image in the bg buffer, the game applies the transparency to whatever's already on the screen when redrawing the background, causing a ghosting effectt of whatever was previously on the screen
- Using bgcopy can fix this issue, assuming the current screen buffer does not contain any tranparency
- You may need to fill the screen with a no-transparency image (like 'black') before using bgcopy

InDevelopment/ManualUpdates/0.utf

@@ -183101,7 +183101,7 @@ bg homing6,80
 ;wait 200
 
 
-
+bgcopy ; fix ghosted text on screen due to transparent homing images drawn with bg command
 ;se2v 36,100
 ;bg white,1
 ;bg black,2
@@ -238870,9 +238870,9 @@ bg black,22
 advchar "09"
 langjp:dwave_jp 0, kir_4e216:「………そんなこと、あるわけがない。@:dwave_jp 0, kir_4e217:………あれはきっと、お父様の友人か何か。@:dwave_jp 0, kir_4e218:…それが、予め食堂のどこかに隠れていて、手品的に突然姿を現して私たちを驚かせただけなんだわ。@:dwave_jp 0, kir_4e219:………そう考えなくちゃ、あのめちゃくちゃを説明できない。」\
 langen:dwave_eng 0, kir_4e216:^"......There's no way that's what happened.^@:dwave_eng 0, kir_4e217:^  ......Those were obviously Father's friends or something.^@:dwave_eng 0, kir_4e218:^  ...They just hid somewhere in the dining hall beforehand and used some tricks to appear suddenly and fool us.^@:dwave_eng 0, kir_4e219:^  ...There's no other way to explain something as screwed up as that."^\
-
+bg black,1 ; fill buffer with black before appliyng transparent Homing6 image
 bg Homing6,22
-
+bgcopy ; fix ghosted text on screen due to transparent homing images drawn with bg command
 advchar "-1"
 langjp　しかし、６人の頭を砕く時に、黄金の矢が室内をぐるぐると飛び回った。@
 langen^But when those six had had their heads blown apart, a golden arrow had flown around and around the room.^@