Remove HTML::Parser from what is shared to PG.

`HTML::Parser` was shared into the safe compartment, and its
`parse_file` method opens and reads whatever path it is given, bypassing
the permitted_read_dir restriction. Thus giving any PG problem arbitrary
file read. It is not actually used by PG, and so that is removed from
the modules that are shared. Note that the `HTML::Entities` package
which is part of the `HTML::Parser` package on CPAN is still shared and
is used.

Author: drgrice1

conf/defaults.config

@@ -1222,7 +1222,6 @@ $pg{specialPGEnvironmentVars}{problemPostamble} = { TeX => '', HTML => '' };
 ${pg}{modules} = [
 	[qw(Encode)],
 	[qw(Encode::Encoding)],
-	[qw(HTML::Parser)],
 	[qw(HTML::Entities)],
 	[qw(Encode)],
 	[qw(Exporter )],