Implements unit tests

Calls purge() method when setting cache range or data series of a variable

Implements purge() method for DataSeries

Adds erase() method for ArrayData and DataSeries

Adapts iterator to be MoveAssignable This will be necessary for purge method (using std::remove_if())

Adapts SqpIterator to make non-const iterators

Merge branch 'feature/MergeFix' into develop

Adds vera exclusions

Updates merge() method (2) Adds methods to be compatible with std::set_union()

Updates merge() method (1) Uses a delegate to perform the operation