Make types a bluish green, for more contrast with strings, so that the
latter can be made greener, for more contrast with the yellow keywords.
Make the main keywords bluer and less bright, and unbold and soften the
yellow ones. Soften the comments too.
Reference for case-insensitivity:
https://www.postgresql.org/docs/14/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS
Also, colorize comments more readably (on a dark background), and
schemas less yelling, and languages more distinct from keywords.
And add a few more keywords, like IS and NULL.
Also, combine some keywords that can only occur together.
And drop a few that are probably rare, like LARGE OBJECT.
Reference:
https://www.postgresql.org/docs/14/bookindex.html
And use a more readable color -- blue is too dark on a black base.
Regular expressions in SQL are not written between // or %r{},
strings are not written between <> or %Q{} or anything similar,
and comments do not start with # -- and officially not with //
either, but some dialects seem to allow it.
This fixes https://savannah.gnu.org/bugs/?61381.
Bug existed since version 2.4.2, since the SQL syntax was included.
