message: add .ofStringAliasArray and .ofStringListArray to Column
diff: @@ -37,7 +37,7 @@ namespace Column {
  export type Coordinate = { '@type': 'coord', T: number } & Base<'float'>
  export type Tensor = { '@type': 'tensor', T: Tensors.Data, space: Tensors.Space, baseType: Int | Float } & Base<'tensor'>
  - export type Aliased<T> = { '@type': 'aliased', T: T } & Base<'str' | 'int'>
  + export type Aliased<T> = { '@type': 'aliased', T: T } & Base<T extends string ? 'str' : 'int'>
  export type List<T extends number|string> = { '@type': 'list', T: T[], separator: string, itemParse: (x: string) => T } & Base<'list'>
  export const str: Str = { '@type': 'str', T: '', valueType: 'str' };
  @@ -137,6 +137,14 @@ namespace Column {
  return arrayColumn({ array, schema: Schema.str });
  }
  + export function ofStringAliasArray<T extends string>(array: ArrayLike<T>) {
  + return arrayColumn<Schema.Aliased<T>>({ array, schema: Schema.Aliased(Schema.str) });
  + }
  +
  + export function ofStringListArray<T extends string>(array: ArrayLike<T[]>, separator = ',') {
  + return arrayColumn<Schema.List<T>>({ array, schema: Schema.List<T>(separator, x => x as T) });
  + }
  +
  export function ofIntTokens(tokens: Tokens) {
  const { count, data, indices } = tokens
  return lambdaColumn({
  