r24495: Add a function lp_canonicalize_parameter: It takes a name of a parameter

r24495: Add a function lp_canonicalize_parameter: It takes a name of a parameter
and produces the "canonical" (or main) name of the parameter (the one
synonym that does not have the flag FLAG_HIDE). The function also sets
a flag as to whether the synonym is a reverse boolean synonym.

Add some functions for the handling of string representations of boolean
values: return the canonical string representation of a bool, invert
a bool given as a string, canonicalize a bool given as a string.

Michael
(This used to be commit 113ac07199aaf2271af6eba2611dad429ee4c416)