Fix the compression algorithm to always be at least as efficient as the one used by Rock Raiders

[Merigrim]

While the FLH-files created by FlicTool can be read by Lego® Rock Raiders just fine, their file sizes are most of the time larger than the original files shipped with the game.

The current algorithm always recognizes repeated pixels as well as pixels that haven't been updated since the last frame in the delta frames, creating appropriate packets for them. However, this is not always optimal since every packet requires additional bytes describing copy/repeat length as well as pixels to skip.

This can be fixed by updating the algorithm to recognize scenarios where inserting a repeat packet or skipping single pixels would be detrimental to the output filesize.