Set v2.0.0-beta.1 version, beta flag and changelog.

Bump version to 1.1.5 and update changelog.

Bump version to 1.1.4 and update changelog.

Bump version to 1.2.3 and update changelog.

Merge pull request bbcmicrobit#87 from microbit-sam/1.1.2-clean

Python Editor changes 1.1.2

Merge pull request bbcmicrobit#86 from microbit-sam/1.1.1-clean

Python Editor changes for 1.1.1

Merge pull request bbcmicrobit#85 from microbit-sam/1.1.0-clean

Python Editor 1.1.0 changes

Merge pull request bbcmicrobit#84 from microbit-sam/1.0.0-clean

Integrate changes from microbit-foundation 1.0.0 tag