Fix case sensitivity when matching tags

(now insensitive again)
Also group case-different tags together when listing

include/internal/catch_test_case_info.h

@@ -37,6 +37,7 @@ namespace Catch {
         std::string className;
         std::string description;
         std::set<std::string> tags;
+        std::set<std::string> lcaseTags;
         std::string tagsAsString;
         SourceLineInfo lineInfo;
         bool isHidden;