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.
Tomasz Wlostowski
John Beard