beremiz

file isExecutable
fix bug with indelible values in some 'optional' fields in project properties panel

only 'required' fields should be indelible
<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"/>