- Added the `ThemeSupport class`, with methods to add and get
theme support options.
- It also has a new `add_default_options` method that adds the
options under a `_defaults` key.
- The `WC_Twenty_*` classes now use `ThemeSupport` instead of
the `add_theme_support` function to define image and thumbnail sizes.
- The values are defined as default options.
- The `WC_Shop_Customizer` class now uses `ThemeSupport` instead of
`wc_get_theme_support` to check if image and thumbnail sizes UI
should be rendered.
- The check is made excluding default values.
With these changes the UI to change the image and thumbnail sizes
is hidden only if the options are added as non-defaults elsewhere.
Additional changes:
- The code of the `wc_get_theme_support` function is replaced with
a simple call to `get_option` in `ThemeSupport`.
- Added the utility class `ArrayUtil`.
Nestor Soriano