tutorials python: commented samples and more detailed pages for windows samples

https://bugzilla.gnome.org/show_bug.cgi?id=677897
tutorials <javascript>: Improved the explanations on the beginner page index
tutorials C: Togglebutton sample/page
Add C togglebutton.c and mallard page to Makefile.am
tutorials python: corrected pages for window widgets
tutorials <javascript>: Added Gtk.CheckButton code sample and documentation page
Add JS checkbutton code file and mallard page to Makefile.am
tutorials python: commented samples and better pages for display widgets
tutorials python: display widgets' pages corrected
tutorials python: pages for window widgets with sections
tutorials python: window widgets' pages corrected
tutorials C: Spinner sample and page
Added C spinner example files to Makefile.am
tutorials C: Entry sample and page
Updated Spanish translation
Updated French doc translation
tutorials <javascript>: Removed line numbers from partial code snippet
tutorials <javascript>: Added Gtk.RadioButton code sample, screenshot, and Mallard page
Added JS radiobutton example files to Makefile.am
tutorials C: Dialog sample and page and Makefile mod