Issue #193, 'Less Than' prepare failing

Add test provided in issue #193, simplified, unprepared and prepared, plus > and <>.
Fix issue, 'Less Than' prepare failing

Do the right thing when getting out of a possible full text match token (cherry picked from master).
Revert earlier fix (which broke full text match operators).
Query Rewriter Tests

Add test from issue #190, plus a couple more, to demonstrate rewriter broken by certain comments (cherry picked from master).
Query Rewriter

Properly handle comments in queries (cherry picked from master).
Merge branch 'release-2.1.0' of https://github.com/npgsql/Npgsql into release-2.1.0

Conflicts:
	tests/CommandTests.cs