wayland: Fix indentation
wayland: Add basic input support
wayland: Build with -pthread
examples/boing: Add ball-follow-cursor functionality

Make it so that in the boing example, when the user clicks, the ball
follows the mouse cursor.
x11: Move KeySym to unicode converter out of x11 backend

To be used by the Wayland backend.
wayland: Add keyboard support

Adds libxkbcommon as a dependency when enabling the Wayland backend.
Merge branch 'wayland-input' of https://github.com/jadahl/glfw