message: Create changelog for V4.0
diff: +## X.Y.Z (INSERT_DATE_HERE)
  +
  +#### Breaking Changes
  +
  +- [BREAKING_CHANGES For V4.0](http://sap.github.io/chevrotain/docs/changes/BREAKING_CHANGES.html#_4-0-0)
  +
  +#### Major Changes
  +
  +- [Concrete Syntax Tree creation is now enabled by default.](https://github.com/SAP/chevrotain/issues/819)
  +
  +#### Minor Changes
  +
  +- [The Parser's constructor no longer accepts a Token vector as the first argument.](https://github.com/SAP/chevrotain/issues/785)
  +- [Runtime infinite loop detection in iterations.](https://github.com/SAP/chevrotain/issues/625)
  +- Small (~5-10%) performance improvements and optimizations.
  + - [Use ES6 Maps(if available) for faster lookahead functions caching.](https://github.com/SAP/chevrotain/issues/812)
  + - [Remove automatic collection of return values for iterations.](https://github.com/SAP/chevrotain/issues/784)
  +
  +#### Bug Fixes
  +
  +- [Stack overflow during grammar analysis.](https://github.com/SAP/chevrotain/pull/816).
  +
  ## 3.7.4 (7-30-2018)
  #### Bug Fixes
  #### Breaking Changes
  -- [See BREAKING_CHANGES.md](https://github.com/SAP/chevrotain/blob/master/BREAKING_CHANGES.md#300)
  +- [BREAKING_CHANGES for V3.0](http://sap.github.io/chevrotain/docs/changes/BREAKING_CHANGES.html#_3-0-0)
  #### Major Changes
  #### Breaking Changes
  -- [See BREAKING_CHANGES.md](https://github.com/SAP/chevrotain/blob/master/BREAKING_CHANGES.md#200)
  +- [BREAKING_CHANGES for V2.0](http://sap.github.io/chevrotain/docs/changes/BREAKING_CHANGES.html#_2-0-0)
  #### Major Changes
  