Handle key names consistently

Handle key names consistently

We treat the key names as fixed length, non NUL terminated strings of
length XkbKeyNameLength, and use the appropriate *Text functions to
print them. We also use strncpy everywhere instead of memcpy to copy
the names, because it does some NUL padding and we might as well.

Signed-off-by: Ran Benita <ran234@gmail.com>