message: Prepare changelog for v0.13.0
diff: +Changes in [0.13.0](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.13.0) (2018-07-30)
  +=====================================================================================================
  +[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.13.0-rc.2...v0.13.0)
  +
  + * Fix composer bug where cursor position would change when Riot regained focus
  + [\#2093](https://github.com/matrix-org/matrix-react-sdk/pull/2093)
  + * Fix persistend element location not updating
  + [\#2094](https://github.com/matrix-org/matrix-react-sdk/pull/2094)
  + * Slate Fixes 42?
  + [\#2089](https://github.com/matrix-org/matrix-react-sdk/pull/2089)
  +
  Changes in [0.13.0-rc.2](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.13.0-rc.2) (2018-07-24)
  ===============================================================================================================
  [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.13.0-rc.1...v0.13.0-rc.2)
  