Added missing file m4/ax_cxx_compile_stdcxx_11.m4

This defines the AX_CXX_COMPILE_STDCXX_11 macro used to generate command
line options for compiling C++11 code.

Signed-off-by: Morten Hustveit <mortehu@google.com>
Make KeyInfo inherit std::pair<unsigned, unsigned>

This saves us from having to implement a comparison operator, but
unfortunately not a hash function.

Signed-off-by: Morten Hustveit <mortehu@google.com>
Remove special processing of the space key

Firstly, I kept writing non-breaking spaces accidentally.  Secondly, X11
sends space characters as expected by default, so we can handle space
the same way as any other character.

Signed-off-by: Morten Hustveit <mortehu@google.com>