Bio/SeqFeature/Generic.pm: Updated Start, End and Length subroutines
to handle circular sequences that have been cut by origin
(e.g., join(5075..5386,1..51))). It can be detected when a subloc ends
in the last nucleotide of the primary sequence and the next subloc starts
at the first nucleotide in the same strand
t/SeqFeature/Generic.t: Fixed a test of circular sequences with a wrong
end coordinate and deleted TODO since the circular tests now pass