remove depreciated gui_local.[ch]xx:

remove depreciated gui_local.[ch]xx:
- drop unused parts (MouseQuat/GuiQuat)
- move "old-reinit-dialog" fgcommand to fg_command.cxx under new name
  "reset" for now. (May later get merged with fgcommand "reinit".)
- move reInit() to fg_init.cxx: This was used by Shift-Esc and
  Menu->File-Reset (via fgcommand "old-reinit-dialog"). We have already
  a similar function fgReInitSubsystems() in fg_init.cxx, so these two
  functions will probably get merged later.)