Add bitfield helper functions

Taken from libevdev-util.h and modified to work with arrays of unsigned chars
Add NCHARS helper macro

(Forgot to add this in the previous commit :( )
Remove normalization

I agree with some of the points made on the mailing list, we probably shouldn't
be handling normalization in libinput
Replace axis_info with bitfield and use evdev for getting axis values

AXIS_FRAME events aren't really emitted anymore for axis updates, might separate
this later into a different logical change but right now I don't think we're
going to be going through with keeping them anyway.
Merge remote-tracking branch 'upstream/master' into axis_info_change

Bringing this branch up to date. Nothing to see here.
Merge branch 'carlos_cleanup' into axis_info_change

Conflicts:
	src/evdev-tablet.c
Merge branch 'carlos_cleanup' into axis_info_change
Convert axis values to fixed width integers before returning
Normalize pressure and tilt axes