Add Camera class (#145)

* Create Camera class with basic attributes

* Test Camera's core attributes

* Add extrinsic_matrix, undistort, and project

* Add tests for extrinisic_matrix, undistort, project,and aliases

* Conform to pydocstyle

* Add method to link Camera to Video

* Test Camera to Video link

* Convert points to float before cv2.undistortPoints

* Docstring clarification and string spelling

* Retain points shape when project

* Test points shape is retained on project

* Add to/from dict methods

* Test to/from dict methods

* Add get_camera and videos to RecordingSession

* Retain points dtype on project

* Test points dtype is retained on project

* Increase test coverage

* Improve docstrings