add screwdriver plugin

The screwdriver plugin is activated once a configurable button on the
wiimote (B by default) is pressed and held. Turning the wiimote
generates key events as long as the button is held down and the wiimote
is being turned. The threshold for indicating a new event is
configurable. The movement resembles the use of a screwdriver and can be
for example be used to regulate the volume of a media player system,
which feels natural and intuitive.
-
added processing of drums controller data
corrected turntables rotation data
initial motionplus pointer support
Update the default gamepad configuration to proper button mappings. The dpad is a hat switch, not the sticks.
Change description from gameport to gamepad.
Merge branch 'master' of https://github.com/seierstad/cwiid
Merge branch 'mplus-pointer' of https://github.com/derf/cwiid

Conflicts:
	wminput/main.c
Merge branch 'patch-1' of https://github.com/md-5/cwiid
Merge branch 'screwdriver' of https://github.com/wertarbyte/cwiid

Conflicts:
	wminput/plugins/Makefile.in
Documentation updates