v3.0.22

Added support for activity stream, global search and note thread access

• Added a new method text_search(), which allows an API client to access the Shotgun global search and auto completer.
• Added a new method activity_stream_read(), which allows an API client to access the activity stream for a given Shotgun entity.
• Added a new method note_thread_read(), which allows an API client to download an entire note conversation, including replies and attachments, using a single API call.
• Added an experimental mockgun module (in the lib submodule), which can be used to emulate the Shotgun API, for example inside unit test rigs.
• Improved existing docstrings, added some missing docstrings, fixed some spelling and grammar issues.
• Minor adjustments to existing unit tests to improve encapsulation.