[bugfix] Label default font size as 24. Fixes NEMO#705.

[glacier] Checkbox implemented with Switch spec

cleanup

[label] Label with example page.

[feature] Added spinner

The spinner behaviour is not perfect yet: it can
be interrupted with two faded blue dots when transitionning
to finished state.

[cleanups] Removed old JS based themes

[tools] Adds generate.sh

generate.sh is a helper script that calls themehelper and
move the file automatically.

Add Page component and update ApplicationWindow and examples gallery

Add ApplicationWindow, ui rotation handling, and update examples accordingly

We may consider renaming the component, but anyway:
ApplicationWindow includes a page stack (StackView) which handles
the pages of the application.

ApplicationWindow includes an Item handling UI rotations,
and offers allowedOrientations (and other useful properties)
to help the dev handle rotation locking.

[livecoding] Add LiveCoding arena to examples gallery

This is to speed up the development of new UI controls,
I'm sure you'll like it :)

[button] Replace dirty hack with a better, more reliable one

[styling] Add ToolBarStyle and its corresponding theme object

[styles] Added ToolButtonStyle

Added support for C++ theming components

This commit imports work done for having C++ based
theming, exporting a C++ Theme singleton object,
and C++ object for each component, starting with
the button.

It also includes the new theming system, using JSON,
and a tool to generate new components based on a
description file.

[textfield] Textfield styling

[components] basic Slider and ProgressBar with reusable groove