Added several libinput config options.
In weston.ini, the new options are called tap_and_drag, tap_and_drag_lock, disable_touchpad_while_typing, middle_emulation, left_handed, rotation, accel_profile, accel_speed, scroll_method, natural_scroll, and scroll_button.
Fixes #172 (closed).
STATUS: After further testing with a USB mouse, I have confirmed that everything except for rotation is working. I don't have the hardware to test rotation.