Use a mapping table to map xfree86 keycodes to evdev keycodes and obtain
consistent keysyms for keymaps. This way, it is now possible to generate
correct keymaps when evdev driver is used on host.
Add support for combining shift & caps lock keys with altgr so that
capital national characters can be written. There was some support for
shift+altgr in xrdp-keygen but it was never actually used.