Maintenance + Video compression

• Add DXT- and LZ77 based video compression
• Add GBA video decompression examples
• Switch to ImageMagick 7
• Add Diff8 / Diff16 delta encoding
• Support 1- and 2-bit tile data
• Fix index pruning

Version 1.1.0

• Fix video conversion when some files had >= 16 and some had < 16 colors
• Add shift option to shift indices for paletted images
• Add README and LICENSE to release

Version 1.0.1

• Fix single image conversion
• Fix sprite conversion