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'.