re-interpret 'fixed' start/end dicts as fallbacks

further assumption: fixedStartValues and fixedEndValues values
adhere to target type, as well as target units.

in present parsers, fixedStartValues and fixedEndValues is only used for
strings, so this change should be backwards-compatible

common/python/nomadcore/simple_parser.py

@@ -588,8 +588,9 @@ class CompiledMatcher(object):
             result_dict[k_converted] = v_converted
         if self.matcher.fixedStartValues:
             for k,v in sorted(self.matcher.fixedStartValues.items()):
-                k_converted, v_converted = self.addStrValue(parser.backend, k, v)
-                result_dict[k_converted] = v_converted
+                if k not in result_dict:
+                    v_converted = self.addValue(parser.backend, k, v)
+                    result_dict[k] = v_converted
         if self.matcher.forwardMatch:
             logger.debug("handleStartMatch of %s on (%s) pushing back line", self.matcher.desc(),line)
             parser.fIn.pushbackLine(line)
@@ -608,8 +609,9 @@ class CompiledMatcher(object):
             result_dict[k_converted] = v_converted
         if self.matcher.fixedEndValues:
             for k,v in sorted(self.matcher.fixedEndValues.items()):
-                k_converted, v_converted = self.addStrValue(parser.backend, k, v)
-                result_dict[k_converted] = v_converted
+                if k not in result_dict:
+                    v_converted = self.addValue(parser.backend, k, v)
+                    result_dict[k] = v_converted
         return result_dict
 
     def annotate(self,match,line,parser,matcher,targetStartEnd):