add LodePNG to base, implement PNG handler for pic.lua
add giflib and corresponding interface to pic.lua
bugfix Makefile: deletion of bad download libjpeg-turbo

A copy and paste leftover is corrected
Merge pull request #269 from hwhw/master

PNG and GIF file handling for pic.lua
Handle the Kobo timing workarounds.

Also, always wait for submission on Kindles for FULL updates,
that bit of logic got lost when I killed the wait_for_full_marker flag.