Changelog for `lambda-notebook`

[0.6.6] - Bugfix release - 2021-10-11

New features:

added an explicit changelog
experimental support for derivations shown using svgling trees
full support for installation in site-packages, better kernel installation

Fixes, improvements, changes (highlights):

improve derivation rendering
improve cross-browser compatibility
improve error messaging and handling of composition failures

[0.6.7] - Vacuity improvements - 2021-10-18

New features:

composition rule for index percolation in tree composition
composition rule for vacuous nodes (with content=None)

Fixes, improvements, changes (highlights):

improve and generalize lang.Binder behavior
enable svgling for internal tree drawing
improvements to the relative clause notebook

[0.6.8] - Vacuity improvements - 2021-10-18

Fixes, improvements, changes (highlights):

correctly pin the right traitlets version