Wrapping gstmm Gst::Event classes among other things

[José Alburquerque <jaalburquerque cox net>]

I've been working on wrapping the Gst::Event classes (similar to the 
Gst::Message classes) among other things in gstmm (such as using 
Glib::ustring in places where std::string is used).  I'm afraid the 
changes are so many that the e-mail is too big to get through the list 
so I'm attaching the changes I've done.  I'm also sad to report that svn 
has not been working for the last few days so I had to use 'svn stat' to 
generate the changlog manually.  These are the changes:

   * examples/ogg_player_gtkmm/PlayerWindow.cc: modified to remove bus
   watch when PlayerWindow is destroyed (in destructor)
   * examples/ogg_player_gtkmm/PlayerWindow.h: added destructor (to
   remove bus watch) and watch_id variable definition (to store bus watch
   id)
   * gst/src/bin.ccg: changed std::string usages to
   * gst/src/bin.hg:  Glib::ustring
   * gst/src/bus.ccg: added remove_watch() method and modified
   add_watch() to return a watch_id
   * gst/src/bus.hg: modified add_watch() declaration to return unsigned
   int and added a remove_watch() method
   * gst/src/caps.hg: used Glib::ustring instead of std::string
   * gst/src/element.ccg: removed handwritten sate_get_name() and
   state_change_return_get_name() methods to use _WRAP_METHOD .hg file
   instead
   * gst/src/element.hg: used _WRAP_METHOD for state_get_name() and
   state_change_return_get_name(); used Glib::ustring instead of
   std::string
   * gst/src/enums.hg: alphabetized enums; added EventType, TagMergeMode
   and TagFlag
   * gst/src/event.ccg: wrapped GstEvent
   * gst/src/event.hg: wrapped GstEvent
   * gst/src/format.ccg: used Glib::ustring instead of
   * gst/src/format.hg:  std::string
   * gst/src/message.ccg: added MessageAsyncStart::parse() method
   definition
   * gst/src/message.hg: cleaned up spacing
   * gst/src/pad.ccg: used Glib::ustring instead of
   * gst/src/pad.hg:  std::string
   * gst/src/padtemplate.ccg: used Glib::ustring instead of
   * gst/src/padtemplate.hg:  std::string
   * gst/src/pipeline.ccg: used Glib::ustring instead of
   * gst/src/pipeline.hg:  std::string
   * gst/src/structure.ccg: used Glib::ustring instead of
   * gst/src/structure.hg:  std::string and added parameter names in .hg
   file
   * tools/m4/convert_gst.m4: added a GstEventType conversion macro

-Jose