* Refactor: Create subpackage 'suggestions'

* Candidates view: Status message when no dictionary installed

Show a message on the candidates view instead of leaving it empty. A
button points to the dictionary installation activity.

* Add an option to disable the suggestions

* Refactor: Remove Config.should_show_candidates_view

This was moved to EditorConfig.

* Don't disable text suggestions in some text boxes

* Suggestion text size matching settings

The candidates view height is based on the height of keyboard rows and
the suggestion text size is based on the size of labels on the keys.

This is influenced by symbol size and keyboard height options.

The calculation for the size of each rows now avoid making the keyboard
bigger than the screen if the Keyboard Height option is unusually high.

The height calculation with the default settings is changed slightly, it
is now assuming that a layout is 3.95 rows high instead of 4. This is
because the bottom row is usually 0.95% the size of other rows.

This is due to Paint.setColor overriding any alpha value set with
Paint.setAlpha. Bug was added in 653c598.

This moves some computations that used to be done during onDraw into the
new Theme.Computed class. This also removes Paint objects from the Theme
class, making it data-only.

This is a requirement for making some keys render differently.

This adds the new 'anticircle' attribute to layouts '<key>' elements
that configure the key to send when doing a anti-clockwise circle
gesture on it.

Labels are drawn the same way as indication.

Updated docs.

Keys that are not in the pending compose sequence are greyed out with
the new 'FLAG_GREYED' flag.

Themes do not dim secondary keys the same way due to the "offset"
mechanism. Instead, use a ratio that is the same for every themes.

It's still possible to override this ratio per theme.

Themes can define the color of each borders independently. Every borders
must have the same width for now. It's possible to set a different width
when the key is activated, thought this is only used to remove borders.

The 4 themes are updated to take advantage of borders.