Basic launcher setup to run *.flow files in Eclipse

Allows files edited with the *.flow editor to be launched directly
in Eclipse (select a *.flow file -> 'Run' -> 'Run As' -> 'Metatext
Workflow'). The current implementation has several limitations:

- Metaflow dependency was created with a patched 'pom.xml' for
`mvn clean assembly:assembly` in metaflow (jar-with-dependencies)
and added to metatext as a jar dependency
- With the metaflow dependency, the language infrastructure can't
be generated in metatext (remove dependency temporarily to
re-generate artifacts)
- The 'metaflow-pipe.properties' file was created and added to the
jar manually (otherwise it is overwritten by the most recent file
with the same name from any project in the metaflow dependencies)
- Paths in the flow file (input, morph definitions, etc.) need to
use absolute paths (the absolute path can be extracted to a var
though)
- Output from flow files to "stdout" is not visible inside Eclipse
(it's printed to the console from which Eclipse was started, if
"-consolelog" is passed)