- direct check of punctuation.
  For example,

      while (!tok.isPunctuation(token::BEGIN_LIST)) ..

  instead of

  while (!(tok.isPunctuation() && tok.pToken() == token::BEGIN_LIST)) ..

  Using direct comparison (tok != token::BEGIN_LIST) can be fragile
  when comparing int values:

      int c = readChar(is);
      while (tok != c) ..  // Danger, uses LABEL comparison!

- direct check of word.
  For example,

      if (tok.isWord("uniform")) ..

  instead of

      if (tok.isWord() && tok.wordToken() == "uniform") ..

- make token lineNumber() a setter method

ENH: adjust internal compound method empty() -> moved()

- support named compound tokens

STYLE: setter method for stream indentation

- silently deprecate 'startsWith', 'endsWith' methods
  (added in 2016: 2b143606), in favour of
  'starts_with', 'ends_with' methods, corresponding to C++20 and
  allowing us to cull then in a few years.

- handle single character versions of starts_with, ends_with.

- add single character version of removeEnd and silently deprecate
  removeTrailing which did the same thing.

- drop the const versions of removeRepeated, removeTrailing.
  Unused and with potential confusion.

STYLE: use shrink_to_fit(), erase()