converter script: Parameterized processor names trip up converter script

[tmadlener]

Marlin seems to support the following construct (taken from CLICPerformance/fcceeConfig/fccReconstruction.xml):

  <constants>
    <!-- CalorimeterIntegrationTimeWindow in ns: 10 or 400 -->
    <constant name="CalorimeterIntegrationTimeWindow"> 10 </constant>
  </constants>

  <processors>
    <processor name="MyDDCaloDigi_${CalorimeterIntegrationTimeWindow}ns"/>
  </processors>

this gets converted into

algList.append(MyDDCaloDigi_${CalorimeterIntegrationTimeWindow}ns)

which is an obvious syntax error in python.