Fix "Libcaf" casing issue in FindLibcaf.cmake.

find_package_handle_standard_args() expects the first argument to be the
name of the Find-module in original casing.  If it's not, it may fail to
do things like abort with a FATAL_ERROR message if REQUIRED was supplied
to the original find_package().
Merge pull request #161 from jsiwek/master

Fix "Libcaf" casing issue in FindLibcaf.cmake.
Fix MinGW build

Fix some issues with CAF on MinGW:
- Correctly initialize networking on Windows using WSAStartup()
- Rename `interface` member function to `message_types` because `interface` is
  a define on Windows (srsly Microsoft?)
- Cast to correct pointer type when using `send` or `recv`
- Fix some warnings caused by using `int` instead of `native_socket_t`

  The issues have been reported by GitHub user xmt.
Reorganize main repository

Add nexus, probe-event, and benchmarks as submodules and cleaned up all CMake
build scripts.
Add Benchmark Suite Options to configure script
Add hook infrastructure to middleman, relates #150
Add missing `anon_send` for typed actors

Move `check_typed_input` to its own header, add `anon_send` for typed actors
and do some cleanup in `local_actor`.
Add `typed_actor::extend` to compose actor types
Add `reacts_to` alias for `replies_to::with<void>`
Build shell as submodule