The libeval grammar can now be rebuilt with "make libeval_grammar".
This is only possible when lemon is installed.
Also a couple of modifications to the lemon grammar to
account for external changes since the grammer was last generated.
Also move the grammar defines into grammar.h - this is how
Lemon produces them, and by manually copying into the target .cpp,
it make automated regeneration impossible.
If ',' is used as decimal separator by the current locale a '.' is also accepted.
Also add support for units "mi", "th" and "in" as described in the documentation of pcbnew.
Fixes: lp:1751315
* https://bugs.launchpad.net/kicad/+bug/1751315
John Beard
Jeff Young
Michael Geselbracht