Revert "gtk2 homebrew: fix package name"

This reverts commit 8b39c72633965cca07b5bb4de401b86a523dfe1e.
Revert "gtk3 homebrew: fix homebrew package name"

This reverts commit de94f3e8acda94c21f93b48e1080da4ce3851bf6.
gi: accept not GType struct as an input argument
gi: accept getting a field value from not GType but GType descendant struct

e.g.: GdkEventXXX structs. They are not GType structs but their parnet
is GdkEvent. GdkEvent is GType union.
gdk3 test: check not only reader but also writer
gtk3: remove needless code
gdk3 test: add a test for key value
gtk3 test: don't build module that doesn't need make
gtk3 test: indent
gi: suppress a warning
gtk3: use cairo_rectangle_int_t instead of GdkRectangle

GdkRectangle is just an alias of cairo_rectangle_int_t.
gi: override existing methods

They are defined from properties. It is OK that they are overridden.
gi: override existing xxx= style setter methods

They are defined from properties. It is OK that they are overridden.
gi: extract as a method
gdk3: remove a needless deprecated

Gdk::Device#input_source is available by property.
gi: add Loader.register_constant_rename_map
gdk3: rename 2BUTTON_PRESS to BUTTON2_PRESS

Because Ruby's constant can't start with a digit.
add initialization with Gdk::RGBA value
this time make it realy work
gdk3 test: Gdk::Event* class initialize takes one argument