add recognition of truecolor escape

More info:
https://github.com/robertknight/konsole/blob/master/user-doc/README.moreColors
according to this document there are also CMY and CMYK colour spaces,
also there is note that separator should be colon, but for simplicity we
use semicolon

Signed-off-by: Amadeusz Sławiński <amade@asmblr.net>
add truecolor support to output

it assumes truecolor escapes code
tested on xterm and st

* xterm seems to produce "broken" output, probably due to mapping
truecolor back to w56 colors

* st works nicely

Signed-off-by: Amadeusz Sławiński <amade@asmblr.net>