Merge pull request #1424 from tresf/stable-1.1

Fix compilation on Apple/Clang (ambiguous fmaf())
Merge pull request #1425 from tresf/stable-1.1

Cleanup fmaf() usage, move to lmms_math.h
Fix master channel peak display
Fix #1427

Conflicts:

	src/core/FxMixer.cpp
	src/gui/FxMixerView.cpp
Update FxMixer.cpp

prevent double adding of jobs