Fix RPM and multiple extruders for BFB style GCode.
Do not use the G92 Exxx for BFB code.
Change extruder swaps for BFB.
Add AGPL notice to engine.
In case of no surface layers in raft - generate interface layer infill on 90 degree angle.
Merge pull request #73 from Ryoko/Raft_interface_generation_angle

Change the angle on which raft interface layer's infill generated.
M103 is stop all extruders.
Merge branch 'master' of github.com:Ultimaker/CuraEngine
Merge remote-tracking branch 'origin/master' into speedrefactor

minor conflict in fffProcessor.h