Add macro for CUP

• New macro for Java CUP #6

  • see documentation at cup
  • see example calculator

• Improved documentation

See all changes in milestone v2

N.B. This macro forces you to define //third_party/cup:cup_bin

You can add a BUILD file third_party/cup/BUILD with content

alias(
  name = "cup_bin",
 actual = "@jflex_rules//third_party/cup:cup_bin",
)