Oops, exporting CXX for AC_CONFIG_SUBDIRS doesn't work if the user specified their own CXX, in which case their version will be in ac_configure_args and will take precedence.  We'll have to modify ac_configure_args.

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.

Disable use of unit analysis (via kj::Quantity) by default (since it has some overhead), but enable it specifically for dev builds.

Fix capnpc-capnp.c++, which appears to have rotted (issue 15).  Should probably write a test at some point...

Don't check uncaught_exception at throw time because catchExceptionsIfUnwinding() is the correct way to handle it.

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