beremiz

file isExecutable
if there is no users matiec installation, then use system path to run iec2c

search for matiec libraries in system path as well

Closes #29
<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"/>