"identifiers" pga3 patch

Dave,

From the SQL docs (1.1.1): "SQL identifiers and key words must begin with a
letter (a-z, but also letters with diacritical marks and non-Latin letters)
or an underscore (_). Subsequent characters in an identifier or key word can
be letters, digits (0-9), or underscores, although the SQL standard will not
define a key word that contains digits or starts or ends with an
underscore."

Do we have a function built yet that checks for this in pga3 yet? If not, I
built one and stuck it in the globals. Here are the patches for misc.h and
misc.cpp.

-Keith