Add regression tests for conditions and comments

Add regression tests for conditions and comments

Fix one case where #else was not corerctly processed and simplify the
conditions logic.

Fix parsing of day and month names in the locale specified in the calendar
file. The previous version would expect those names to match the locale of
the user.

Mention that comments are now correctly processed and that // is supported
in addition to /* ... */.

MFC after:	3 days