Remove the majority of the Gtk related code

- rip all Gtk code from qt-gui.cpp
- don't compile Gtk specific files
- don't link against Gtk libraries
- don't compile modules we don't use at all (yet)
- use #if USE_GTK_UI on the remaining files to disable Gtk related parts
- disable the non-functional Cochran support while I'm at it

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

planner.c

@@ -685,9 +685,11 @@ void plan(struct diveplan *diveplan, char **cached_datap, struct dive **divep, c
 		stopidx--;
 	}
 	add_plan_to_notes(diveplan, dive);
+#if USE_GTK_UI
 	/* now make the dive visible in the dive list */
 	report_dives(FALSE, FALSE);
 	show_and_select_dive(dive);
+#endif
 error_exit:
 	free(stoplevels);
 	free(gaschanges);