• Break change snippet support reworked: support nest snippets, independent
  session in each buffer and lots of fixes.
• Break change diagnostic list now sort by severity first.
• Add commands: :CocUnInstall and :CocOpenLog
• Add cterm color for highlights.
• Add line highlight support for diagnostic.
• Add coc.preferences.fixInsertedWord to make complete item replace current word.
• Fix check confirm not works on vim sometimes.
• Fix check of vim-node-rpc.
• Fix preselect complete item not first sometimes.
• Improve completion sort result by consider more abort priority and recent
  selected.
• Improve colors module, only highlight current buffer and when buffer changed.
• Improve doc/coc.txt