Other codepages, extension drag'n'drop, new text thread for clipboard

Features:
You can now use codepages other than Shift-JIS and UTF-8. Put them in H/R code right after the text encoding type e.g. /HB936#-8@4A32C0 (this would use codepage 936 - simplified chinese).
You can also modify Default_Codepage in Textractor.ini.
Extension system now has its own dialog. You can drag'n'drop to rearrange or add extensions.
Your clipboard is now captured into its own text thread.

Bugfixes:
Fixed weird crashes with Bing Translate.
Made Bing Translate compatible with Wine.
Textractor now closes all windows made by extensions when main window is closed.
Other general stability improvements.