Added encode_pg_and_html subroutine that encodes all html, ev3 and pgml special characters.  I also made a bunch of changes to different files to use the new subroutine.
Merge branch 'master' of https://github.com/openwebwork/pg into encodebug2

Conflicts:
	macros/PG.pl
Fixing somethings and reverting some unintended changes.
Fixing my fixes.
More polish on encoding pg and html.
Workaround fix for encoding bug
Reverting unneccessary changes.
Reverting additional changes.
Merge pull request #168 from goehle/encodebug2

Encode PG Special Characters
Merge tag 'PG-2.8.1+' of https://github.com/openwebwork/pg

Conflicts:
	macros/PGbasicmacros.pl