Split the configuration dialog off into its own file and mostly decouple
it from the subtitle format.
Save last used export settings to options and restore them the next time
the dialog is opened.
Use libaegisub for charset conversion and IO rather than wxWidgets.
Use libaegisub's line-wrapping logic and finish implementing all of the
various wrapping modes.
Make unchecking the "Translate alignments" checkbox do something.
Originally committed to SVN as r6636.
