#878 Add Josep Maria Blasco's Rexx parser to ooRexx

[Rony G. Flatscher]

Josep Maria Blasco's Rexx parser toolset (pure ooRexx) can parse ooRexx, as well as classic Rexx and dialects like Regina or CMS Rexx.
The utility and applicability of this toolset is enormeous for (oo)Rexx programmers.

A "simple" current case: the ooRexx documentation, in the form of XML files, contains many Rexx program listings that can be syntax-highlighted with the Rexx parser's utility programs.

There are numerous interesting applications that become possible to tackle without an extraordinary amount of effort (other than learning the stream and tree interfaces to the parsing results, which is fairly easy).