Image 8-bpp ditherer + native GIF encoder

First: All thanks to Ron van Tilburg for the amazing VB GIF encoder (original post: CodeId=14210. For GIF decoding, check Vlad Vissoultchev's work: CodeId=44216). This simple application lets you import (dither) to 8-bpp bitmaps and save as GIF format. Transparency and trailing comment now supported. About palette imports: only Halftone-216 and optimal palette are allowed, anyway, you could easily add custom palette import.