• Break change: created keymaps use rpcrequest instead of rpcnotify.
• Break change: snippets provider is removed, use coc-snippets for
  extention snippets.
• Add command: coc.action.insertSnippet
• Fix position of snippets.
• Fix modifier of registed keymaps.
• Fix completion triggered on complete done.
• Fix closure function possible conflict.
• Fix unexpected snippet cancel.
• Fix document applyEdits, always use current lines.
• Fix fail of yarn global command.
• Fix check of changedtick on completion done.
• Fix line used for textEdit of completion.
• Fix snippet canceled by formatOnType.
• Fix CocJumpPlaceholder not fired
• Optimize content synchronize.