addons/namingng.py: Reinstate dict-with-regexps, cosmetic overhaul. (#…

…5824)

`namingng.py` somewhat supported specifying a dict instead of a list for
regular expressions, until the feature was broken by a patch of mine
recently. This PR contains a patch rewriting the feature and expanding
relevant unit tests.

To improve maintainability, a second patch is added that refactors the
code for better readability and structure.

addons/ROS_naming.json

@@ -1,5 +1,5 @@
 {
-    "RE_FILE": {".*[A-Z]": [true, "under_scored"]},
+    "RE_FILE": [".*[A-Z]"],
     "RE_NAMESPACE": {".*[A-Z]": [true, "under_scored"],
     				 ".*\\_$": [true, "under_scored"]},
     "RE_FUNCTIONNAME": {".*\\_": [true, "camelCase"],