This commit turns hint mode into a real mode. This required several
changes:
- In `src/content/hinting.ts`: create a function named getHintCommands
which returns an object containing functions that can be used as ex
commands.
- In `src/content/hinting.ts`: rewriting the `parser` function to have
it check the `hintmaps` object in the config and trigger these if
they're bound to anything. We can't use a generic parser because
vimperator hints need to catch every single keypress, even the ones
that aren't bound to anything and act on them.
- Creating `src/background/hinting.ts`, which just wraps ex commands
from src/content/hintings.ts in a proxy which will forward calls to the
content script.
This commit removes commandline_background.ts. I believe this is useful
because the only thing it did was provide recvExStr, which just
triggered a synthetic "onLine" event the only consumer of which was the
parser. Since we already used controller_background + acceptExCmd in
some places, it made sense to me to directly use controller_background +
acceptExCmd everywhere.
All functions in native_background.ts use browserBg in order to interact
with the native messenger. This means that these functions can also be
used in the content script. This means that there's no point in keeping
these functions in the background/ folder and that there's no point in
having a native_background message type.
