[Paciente8159/uCNC PR#55] Grbl settings emulation

-moved frequency limiting out of the hal to core code
-added basic settings for grbl if startup emulation enabled (this includes $1-it’s not used and always returns 0 and $11-that sets the G64-cosine factor. This value should be between -1 and 1. If 0 it acts as G61-exact path mode and -1 acts as G61.1 exact stop mode)
-$0-max step rate is now used to top limit stepping frequency