message: Add a fake environment
  This enables to complete '\begin{' into
  \begin{$1}
  $0
  \end{$1}
  with a multi-cursor on $1 and completion automatically triggered.
  This can be used to restore the behaviour prior to this PR.
diff: @@ -32,6 +32,16 @@ export class Environment {
  initialize(envs: {[key: string]: EnvItemEntry}) {
  this.defaultEnvsAsCommand = []
  this.defaultEnvsForBegin = []
  + this.defaultEnvsAsName = []
  + const endCompletion: Suggestion = {
  + label: 'Complete with \\end',
  + sortText: ' ',
  + insertText: new vscode.SnippetString('$1}\n\t$0\n\\end{$1}'),
  + command: { title: 'Post-Action', command: 'editor.action.triggerSuggest' },
  + kind: vscode.CompletionItemKind.Function,
  + package: ''
  + }
  + this.defaultEnvsForBegin.push(endCompletion)
  Object.keys(envs).forEach(env => {
  this.defaultEnvsAsCommand.push(this.entryEnvToCompletion(envs[env], 'begin{'))
  this.defaultEnvsForBegin.push(this.entryEnvToCompletion(envs[env]))
  