The old keygrabber API wasn't doing what the users want from a
keygrabber module. With tons of boilerplate code, everything could
be done, but it wasn't trivial.
This commit add a default grabber function that implements the
keybinding API already used by `awful.key` and `awful.prompt`.
It also add syntax candy left and right to make the module "feel"
like a native CAPI object.
Nothing is perfect and some parts, like adding root keybindings, are not
vevy pleasing. However it fulfill its goal when it comes to make
previously non-trivial use case very easy to implement and deploy.
It does not provide much value. The version number is already known to
ldoc globally in the "description" variable.
Signed-off-by: Uli Schlachter <psychon@znc.in>