Like uh, UTF-8 encoding/decoding, some fixes in `calc_brightness`,
some changes in `c_fatal` (it now accepts formatting) and some other
things I of course forgot.
Oh yeah, and module now can signal that something went horrubly wrong
and die. Yay!
* Added `testbuild` target. Used in development to test common
compilers, as well as check for possible issues via OCLint.
* `__{blk,bra}_*` now use state to get palette & other options.
TODO: optimize number of ANSI color codes when fg==bg
Casey