Limited joining collector

[amaembo]

Implement collector which joins stream of CharSequences with given delimiter which may short-circuit when the given length is reached adding the optional ellipsis. Possible features and settings include:

• delimiter CharSequence
• prefix/suffix CharSequences (to fully supercede the JDK Collectors.joining)
• ellipsis CharSequence (default: "...")
• Limit length:
  • by number of chars
  • by number of codepoints
  • by number of Unicode symbols (including combining ones)
  • by custom user function (which probably computes the rendered string width in the UI) (postponed: see Enhance Joining collector #20)
• Where to cut the string:
  • between any chars
  • between any codepoints
  • between any Unicode symbols (see java.text.BreakIterator.getCharacterInstance())
  • between any words (see java.text.BreakIterator.getWordInstance())
  • only before delimiter: "foo, bar..."
  • only after delimiter: "foo, bar, ..."
  • with custom user function (probably using ICU4J BreakIterator, etc.) (postponed: see Enhance Joining collector #20)

Roadmap:

• Implementation draft
• Tests
• JavaDoc
• Benchmarks
• Changes