make it possible to update XSD schema in project controller after new
target PLC is added or removed.

For example:


...
import targets
targets.targets["PLC"] = {"xsd": os.path.join(self.customBeremizPath, "PLCtarget", xsd),
"class": lambda: PLC_target,
"code": {"plc_PLC_main.c": os.path.join(self.customBeremizPath, "PLCtarget", "plc_PLC_main.c")}
}

from ProjectController import ProjectController, GetProjectControllerXSD
ProjectController.XSD = GetProjectControllerXSD()

                  <xsd:element name="Linux">
                    <xsd:complexType>
                      %(toolchain_gcc)s
                    </xsd:complexType>
                  </xsd:element>