Merge pull request #41 from gianmt/master

Add A Gtk.HeaderBar example
Update intersphinx mapping.
Merge pull request #46 from lazka/master

Update intersphinx mapping.
Correct function call typo
Merge pull request #48 from pwaring/patch-1

Correct function call typo
which properties a widget has
fix close button method
Merge pull request #50 from ozzmos/patch-1

fix close button method
Merge pull request #49 from Xoristzatziki/patch-1

which properties a widget has
Fix error in headerbar example

Fixes

    AttributeError: 'gi._gobject.GProps' object has no attribute 'set_show_close_button'
Merge pull request #51 from mgedmin/patch-1

Fix error in headerbar example
Merge pull request #52 from gianmt/master

Add a new Gtk.FlowBox example