update ignores
add is_srs* methods, remove_tag(string)

Added methods to test for srs address types:
    - is_srs0(string): bool
    - is_srs1(string): bool
    - is_srs(string): bool (either SRS1 or SRS0 is ok)

Added method to remove SRS1, SRS0 plus following separator char:
    - remove_tag(string&)
        note that this removes the tag IN PLACE
flesh out the test suite