Separate Gtk related code from core logic: info

Surprisingly straight forward, just a couple of places where we really mix
significant logic with UI code (for example setting the window title).

I had to move amount_selected from display-gtk.h to display.h - I guess
the number of dives that are selected is UI independent. But I wonder if
we still will track this as a global variable in a Qt UI (since the Gtk
selection logic is the main reason this existed in the first place).

Added a new info.h files for the necessary declarations.

This should make no difference to functionality.

Cherry-picked from Qt branch; fixed merge issues mostly caused by
dive_tags and Makefile changes.

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

Makefile

@@ -162,15 +162,15 @@ LIBS = $(LIBXML2) $(LIBXSLT) $(LIBSQLITE3) $(LIBGTK) $(LIBGCONF2) $(LIBDIVECOMPU
 MSGLANGS=$(notdir $(wildcard po/*.po))
 MSGOBJS=$(addprefix share/locale/,$(MSGLANGS:.po=.UTF-8/LC_MESSAGES/subsurface.mo))
 
-OBJS =	main.o dive.o time.o profile.o info.o equipment.o divelist.o divelist-gtk.o deco.o \
-	planner.o planner-gtk.o \
+GTKOBJS = info-gtk.o divelist-gtk.o planner-gtk.o gtk-gui.o
+
+OBJS =	main.o dive.o time.o profile.o info.o equipment.o divelist.o deco.o planner.o \
 	parse-xml.o save-xml.o libdivecomputer.o print.o uemis.o uemis-downloader.o \
-	gtk-gui.o statistics.o file.o cochran.o device.o download-dialog.o prefs.o \
-	webservice.o sha1.o $(GPSOBJ) $(OSSUPPORT).o $(RESFILE)
+	statistics.o file.o cochran.o device.o download-dialog.o prefs.o \
+	webservice.o sha1.o $(GPSOBJ) $(OSSUPPORT).o $(RESFILE) $(GTKOBJS)
 
 DEPS = $(wildcard .dep/*.dep)
 
-
 all: $(NAME)
 
 $(NAME): gen_version_file $(OBJS) $(MSGOBJS) $(INFOPLIST)