Ignore leading/trailing whitespace in test/section specs

The leading/trailing whitespace is problematic because of e.g.
`WHEN` macro having preceeding whitespace for alignment, and it is
generally messy.

Credits to Phil who did lot of the original work.

Closes #1708

include/internal/catch_test_case_tracker.h

@@ -133,6 +133,7 @@ namespace TestCaseTracking {
 
     class SectionTracker : public TrackerBase {
         std::vector<std::string> m_filters;
+        std::string m_trimmed_name;
     public:
         SectionTracker( NameAndLocation const& nameAndLocation, TrackerContext& ctx, ITracker* parent );