message: Mark fields as readonly when possible
diff: @@ -11,18 +11,18 @@ import {SurroundCommand} from './commandlib/surround'
  type DataUnimathSymbolsJsonType = typeof import('../../../data/unimathsymbols.json')
  export interface CmdItemEntry {
  - command: string, // frame
  + readonly command: string, // frame
  snippet?: string,
  - package?: string,
  - label?: string, // \\begin{frame} ... \\end{frame}
  - detail?: string,
  - documentation?: string,
  - postAction?: string
  + readonly package?: string,
  + readonly label?: string, // \\begin{frame} ... \\end{frame}
  + readonly detail?: string,
  + readonly documentation?: string,
  + readonly postAction?: string
  }
  export interface CmdSignature {
  - name: string, // name without leading `\`
  - args: string // {} for mandatory args and [] for optional args
  + readonly name: string, // name without leading `\`
  + readonly args: string // {} for mandatory args and [] for optional args
  }
  function isCmdItemEntry(obj: any): obj is CmdItemEntry {
  