Fix bug in Extruder where speed was not being initialiezed so extruder was not finishing at the same time as XYZ, causing stutters and pauses.
Merge pull request #249 from wolfmanjm/upstreamedge

Fix bug in Extruder where speed was not being initialiezed so extruder w...
Merge remote-tracking branch 'upstream/edge' into working
set to 120MHz
add clause to mbed makefile so adding make SMOOTHIEBETA=0 will enable 120MHz, default will be 96MHz for now