Move all third party code to a "third-party" directory.

Remove NOTICE file now that third party code is explicitly grouped.
Adjust build scripts to use the new third party code location and streamline
cleanup of dependencies managed by Ninja.
Merge pull request #56 from nicksay/third-party

Move all third party code to a "third-party" directory.
Remove deprecated navigation events and update API definition.

Closes #12.
Merge pull request #58 from nicksay/remove-deprecated-events

Remove deprecated navigation events and update API definition.
merge