gui: consolidate colour theme

put more colour used into the odemi.gui constants
change the log text field to use dark them too.
gui: small clean ups
gui comp stream: show hardware excitation/emission settings for filtered colour streams

Seems to work well, but need more tests with multi-band and static streams.

also fix a bug in band center computation
driver andorcam3: clean up

comment is not true with latests SDKs