add ~Pathspec() to cleanup regex contexts
FIX: custom copy c'tor to handle regex contexts
TEST: unit test to ensure proper copy c'tor
Refactor: add DestroyRegularExpressions()
FIX: add assignment operator
TEST: unit test for assignment operator
add TODO C++11 comment
Merge pull request #521 from reneme/fix-pathspec_memory_leak

Fix: Pathspec Memory Leak