Add NEWS.md

Version bump for release.
Set default hashable types.

Merged in cbillington/blacs/deserialise-transition-to-manual (pull re…

…quest labscript-suite#73)

Deserialise transition to manual and implement start_order and stop_order

Bump minor version so devices may rely on support of image outputs

Bumped minor version for release

Merged in cbillington/blacs/defer_worker_imports (pull request labscr…

…ipt-suite#54)

Defer worker imports

Bumped minor version to 2.3.0