Fix to interleave, updated doctests and change to OP

In order to produce scanning curves I have started to implement residual saturation to the OP algorithm (this is not finished). I have also changed the initial invasion capillary pressures (self._p_inv and self._t_inv) to be infinite. Before if a range of Pc was given to the algorithm which did not span the full range of entry pressures the un-invaded pores and throats were being set to zero pressure and sequence 0. Interleave_data now correctly handles boolean data. I've tried to make it as robust as possible when handling mixed data types not just nans when the data is not found on a particular geometry. However, in order to preserve boolean data at all times it is necessary to effectively ignore non-boolean data when interleaving from geometries that have assigned a property as boolean and non-boolean. I think this will be a rare occurrence but might happen when importing data from other sources. Appropriate messages are sent as warnings when a data conversion happens. I added a doctest to interleave and also fixed some others in vertexops, delaunay and plots. I still get some failures but I will leave them for others to fix.