Scalameta tree pretty printer

Pretty printer for Scalameta trees using Paiges. Improves the built-in Scalameta pretty printer (Tree.syntax) with

• more correct handling of precedence rules, inserting parentheses where necessary.
• line wrapping so that large expressions don't appear in a single line with hundreds of columns.
• ability to preserve comments, enabling syntax preserving tree transforms
• better performance

The end goal of this project is to enable a more powerful refactoring API for Scalafix. Currently, Scalafix rewrites are implemented using a fairly low-level token API, which is error-prone.

Team

The current maintainers (people who can merge pull requests) are:

• Guillaume Massé - @@MasseGuillaume
• Ólafur Páll Geirsson - @olafurpg