Minor fixes to comments in rpc.capnp

Remove a reference to Main, add a comment about the legality of acceptFromThirdParty, and fix a few typos and one pervasive grammatical error.
Add test scripts for MinGW and Android.
Update mega-test, and make tests pass.
Fix uninitialized memory usage found by valgrind.
De-flake timing-dependent test.
Update bootstraps.
MSVC: Fix issues so cmake build works.
Add cmake to exotic tests.
Move cmake files into c++ subdir.

The idea behind the directory organization was that we might have official implementations for other languages in other top-level directories, as siblings to the c++ directory. It seems implausible that we'd use CMake as a meta-build-system over all of these.

Another reason for this change is that the release tarball actually contains only the c++ subdirectory. We probably want to include cmake files in the release.
Include cmake files in automake dist.
Update release script to build Windows package.
Resolve TODO(now|soon) and remove KJ_DBG.
Apparently distcheck and dist-zip will stomp each other if run in parallel.
Improve release script's windows build.
Revamp installation docs, in particular to include MSVC info.
Tweak release.sh some more.
Tweak release.sh some more.
Set mainlaine version to 0.6-dev.
Remove obsolete MSVC stuff.
Merge branch 'master' of github.com:kentonv/capnproto