Clarify licensing, and packaging of runtime only files :
- moved and split targets/typemapping.py into runtime/typemapping.py and runtime/loglevels.py
- added runtime_files.list pointing to files necessary for runtime, and referring to runtime license

          <xsd:attribute name="Command" type="xsd:string" use="optional" default="make -C %(buildpath)s all BEREMIZSRC=%(src)s BEREMIZCFLAGS=%(cflags)s MD5=%(md5)s USE_BEREMIZ=1 FROM_BEREMIZ=1"/>