Add backend notes to CHANGELOG
Merge pull request #1542 from david-christiansen/changelog-updates

Add backend notes to CHANGELOG
Improve pretty-printing of "let"
Vastly improve pretty-printing of definitions in :printdef
Add :printdef support for datatype definitions
Support constructors in :printdef
IDE support for :printdef
Nicer-looking disambiguation in :printdef

Now, it only shows full names in cases of ambiguity.
Merge pull request #1543 from david-christiansen/pprint-printdef

Major improvements to pretty-printing and :printdef
Merge pull request #1544 from david-christiansen/pprint-printdef

Nicer-looking disambiguation in :printdef