fixturegroup: hash usage optimization
qlcfixturemode: do not rebuild a complete vector each time we fetch the heads
fixturehead: rgbchannels and cmychannels container: list -> vector
genericfader: hash usage optimization
rgbmatrix::insertstartvalues: hash usage optimization
qlcfixturemode::channel: less code, same effect
Merge pull request #372 from plugz/rgbmatrix-speedup

Rgbmatrix speedup