Merge pull request #305 from onevcat/develop

Add Chinese localization for CotEditor
Fix selecting inside brackets (fix #304)
Change default syntax style to "Plain Text"
Update changelog
Update license description about legacy Smultron

The latest legacy Sumltiron 2.x was distributed under the terms of the BSD license.

* CELayoutManager *was* based on Sumltron's SMLLayoutManager. However, because it was rewrote a lot on CotEditor 2.0, now the code is completely different. So I've removed the statements.
Add acknowledgement to @onevcat (#305)
Improve popup menus in toolbar for "Text Only" mode
Implement pinch-zoom (close #308)
Refactor CETextView
Fix page guide position