Install schema.capnp and c++.capnp to $PREFIX/include/capnp.  Make sure /usr/include and /usr/local/include are in the capnpc search path.  Fix Makefile bug related to ridiculous gmake implicit rules.  And update the docs a bit.

Apply some capnproto -> capnp renames that didn't happen before, update docs, put samples in a place where they are easy to compile.

Nope, Red Carpet does NOT work.  Back to Maruku, which also does not work, but in a way that is easier to work around.