Merge pull request #285 from evildeeds/gzstream-bugfix

Fixed empty check in gzfile_buffer
Fixed a problem that could cause the gzbuffer to read a byte when requesting 0 bytes.
Fixed an incorrect type conversion casuing negative block-IDs.
Merge pull request #287 from evildeeds/gzstream-bugfix

Gzbuffer bugfix
Merge pull request #286 from evildeeds/color-lookup-fix

Fixed an incorrect type conversion casuing negative block-IDs.
Merge https://github.com/udoprog/c10t