Implement correct behaviour for hints
The Wayland text-input protocol specifies several hints modifying the behaviour of the input. Any number of them may be set at the same time. Some relevant ones (skipping prediction):
Content hint is a bitmask to allow to modify the behavior of the text input.
- switch to uppercase letters at the start of a sentence
- prefer lowercase letters
- prefer uppercase letters
- prefer casing for titles and headings (can be language dependent)
- characters should be hidden
- typed text should not be stored (useful for prediction, but maybe others)
- just Latin characters should be entered
- the text input is multiline
The behaviour should mesh well with whatever comes out of #65