Bump version check for v0.5
Add timer functionality
Fix up cancel and timer a bit
Add arguments checking to `then` callback
Add args checking to Void and RemotePromises `then` and check for double

send in Requests.
Fix cancel methods
Add check that method exists in Capability.__getattr__.

This makes it play nice with hasattr
Add pickling test
Add functionality for using event loops in different threads
Get inheritance working for simple version capabilities
Bump version for 0.5.0-dev
Fix pickling for pypy
Fix error message in version check
Add ability to import modules with dashes or spaces

Any module with underscores in it will now attempt to look for 3 files,
first the original, then with dashes, then with spaces, ie:
import addressbook_v_2_capnp
will search for 'addressbook_v_2.capnp', 'addressbook-v-2.capnp', and
'addressbook v 2.capnp'.
Fix bug in DynamicCapability's dir method
Clarify common problem when C++ Cap'n Proto is not found.

Fixes #27
Fix `to_dict` not converting enums to strings

Fixes #28
Fix `test_to_dict_enum` under Python3
Make pycapnp GIL friendly

Now calling `wait` from one thread will not block all threads
Add thread examples