vast code simplification of GValues, add MutableType module, plug some memory leaks
generalize GValues to handle many more usages. simplify signal_connect -- easy mode is now available, fast mode was unaffected. fix a small memory leak in gc_ref
ensure the type returned by GValue auto-unboxing is exactly what we wanted, without losing information by converting though Julia types. add this information to the README, and some minor GValue-related cleanup
use new mutable type wrapper everywhere, instead of 0-D Arrays, for internal APIs
correct the filter for GObjects in the G_ generator
Merge branch 'master' of github.com:JuliaLang/Gtk.jl
Change MouseHandler callback interface to (widget, event)

This is needed to properly support calls to gtk_menu_popup without
forcing the user to by-pass the whole Canvas MouseHandler API.
Add basic support for menus
Add callback to menu item in tests
Merge pull request #21 from timholy/menu

Basic support for menus
fix some formatting in the README
Use shorter names for constants, expand exports of constants