message: fix slicing math modes
diff: @@ -115,6 +115,9 @@ export class HoverProvider implements vscode.HoverProvider {
  if (tex.startsWith('\\(') && tex.endsWith('\\)')) {
  tex = tex.slice(2, tex.length - 2)
  }
  + if (tex.startsWith('\\[') && tex.endsWith('\\]')) {
  + tex = tex.slice(2, tex.length - 2)
  + }
  return tex
  }
  