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>

info.c

@@ -448,10 +448,15 @@ void update_time_depth(struct dive *dive, struct dive *edited)
 	dive->dc.meandepth.mm = edited->dc.meandepth.mm;
 }
 
-int edit_dive_info(struct dive *dive, gboolean newdive)
+void add_people(const char *string)
 {
-	if (!dive || (!newdive && !amount_selected))
-		return 0;
-
-	return edit_multi_dive_info(dive);
+	/* add names to the completion list for people */
+}
+void add_location(const char *string)
+{
+	/* add names to the completion list for locations */
+}
+void add_suit(const char *string)
+{
+	/* add names to the completion list for suits */
 }