Merge pull request #1467 from am11/master

Release: Version 2.3.3
Merge pull request #1468 from am11/master

Package: Read version from a const
CSS: Add text to duplicate selector warning
Merge pull request #1473 from SLaks/css-fixes

CSS: Add text to duplicate selector warning
JSON: Added completion for "format" property values
CSS: Check properties to rescue from NRE. (#1477)
Merge pull request #1478 from am11/css-inline-comment

CSS: Check properties to rescue from NRE (#1477)
Merge pull request #1470 from am11/master

Feature: CSON support (#1305)