Fix trimming whitespace from Doxygen comments.

Also trim the string (making it empty) if it consists solely of whitespace.

Examples/test-suite/python/doxygen_misc_constructs_runme.py

@@ -45,7 +45,7 @@ may be specified."""
 )
 
 commentVerifier.check(doxygen_misc_constructs.getConnection.__doc__,
-    r""" 
+    r"""
 
 This function returns connection id."""
 )

Source/DoxygenTranslator/src/PyDocConverter.cpp

@@ -117,7 +117,9 @@ static size_t determineIndent(const string& s)
 static void trimWhitespace(string& s)
 {
   const size_t lastNonSpace = s.find_last_not_of(' ');
-  if (lastNonSpace != string::npos)
+  if (lastNonSpace == string::npos)
+    s.clear();
+  else
     s.erase(lastNonSpace + 1);
 }