Other schemas may need this which do not go through a process of removing
old/retired seq region ids in favour of their new ids. When querying by a slice
this is automatically delt with. When fetching by an ID you now need to
force the search on.

Added constrain_to_seq_region for web rendering reasons, where requested slice->expand were flying off the end of chromosomes.

Adding an iterator for subseqs to the Slice object. Means a lot of our code which deals with iteration of slices can delegate to this for its logic.

updated slice test script

Updated slice.t test script

changed some throws to warnings in MultiTestDB

Added a test for ProteinAlignFeatureAdaptor and altered the dnaalignfeature test to work with the alterd base align
feature