Experimental ooRexx 5

Forked from https://sourceforge.net/p/oorexx/code-0/HEAD/tree.

Unlike Executor and Executor5, this repository includes everything from SourceForge: trunk, branches, releases, docs, tests, incubator, and sandboxes.

Documentation:

• Diary
• Instructions to build Executor5-bulk
• Instructions to build ICU4ooRexx (optional)

Extensions:

• RxMessageBox
• String~isASCII
• String~translateInto
• Unicode support

ooRexx 5 bugs fixed but not yet backported:

• [bugs:#2066] ADDRESS with input, child process blocked on stdin when stdin is not ready.
  Diary.

ooRexx 5 feature requests implemented but not yet backported:

• [feature-requests:#868] Better support of EOF in rexxtry.
  Diary.

• [feature-requests:#867] Determine whether a stream is associated with a terminal.
  Documentation.
  Diary.