Make the "human-readable text vs. PSML vs. PDML" choice separate from

Make the "human-readable text vs. PSML vs. PDML" choice separate from
the "text vs.  PostScript" choice.  The "text vs. PostScript" choice
should probably ultimately be done with a generic set of print methods,
to handle various platform-native print mechanisms more cleanly (and
perhaps the dialog box code for "export as {PDML,PSML}" should be
separate from the "export as text"/"print" dialog).

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@11342 f5534014-38df-0310-8fa8-9805f1628bb7