Improper handling of quotes within the comment field

[Blue-Shadow]

SLADE Version: (3.2.1)
Operating System: Windows

Issue Details:
If you assign a thing/linedef/sector/etc. a comment which contains quotes, something like: blah "foo" bar. SLADE doesn't escape those quotes when generating the TEXTMAP lump of the map, which makes the map fails to load in GZDoom with a parsing error. SLADE also becomes unable to load the map, stating that it's invalid.

If you load this file with GZDoom, you'll get this error upon starting a new game on MAP01:

Script error, "MAP01" line 41:
Expected ';' but got identifier 'mysterious' instead.

This is line 41 in the map's TEXTMAP lump:

comment="The "mysterious" lamp";

Which should be like this:

comment="The \"mysterious\" lamp";