Gaps in term dates cause seat data to crash

[inghamn]

Term::getNextTerm fails when there's already a future term in the system, but with a start date that does not line up with the end date of the current term.

Example the current term is 1/1/2015 - 1/4/2017 and the next term after that is 1/7/2017 - 1/14/2019
There's a gap of a few days there. When displaying the seats listing the Term::getNextTerm call will crash.

This is partly because Term::getNextTerm tries to generate the next term if there isn't one. And the fact that it increments by one day past the end date of a term. When it goes to create a new term, there's not enough room in the schedule.