CoolLine 9.1.000-beta3 : Classic, Burning Crusade, Retail backdrop fix + toc bump

CoolLine 9.1.000-beta3

Classic/TBC/Retail packages should be working

Changes:

• Fixes frame backdrop according to game version (should fix #16 & #18)
• Improved version checks : no more "if classic/if retail" branches
• Add a local development build script to check addon packager behavior prior to deliver/release publishing
• Add build CI for BC