Added optional parameter to line_projection() method in geometry.py, so that it can return non-dimensional distance between the line start and line end of the projected point
Bugfix in t2listing skip_to_table_AUTOUGH2() method: history() could fail for AUTOUGH2 listings with no simulation title
Added t2grid demote_block() method
Added documentation for new t2grid demote_block() method
Bugfix in t2listing history()- could fail when returning history from AUTOUGH2 results with short output items out of their original order
Split t2listing setup_short() method into two new ones, setup_short_types() and setup_short_indices().  The latter uses a new method for determining indices of main table items in short output, no longer reliant on indices reported in the listing file
Updated readme and user guide documentation to reflect new layout of github pages- download button has moved
Altered calculation of connection centres, from midpoint to closest point to each block centre in the connection (potentially two 'centres' for each connection, if the connection face isn't orthogonal to the line joining the block centres)
Bugfix in flux_matrix()- recent changes introduced unnecessary reversal of normal vector
Added connection_nodes() method in mulgrids, with better identifcation of connection nodes- properly preserving node order in the first column of the connection
Altered mulgrid layer_plot() and slice_plot() so that flows are not shown in columns with less than 3 nodes
Bugfix in layer_plot() and slice_plot()- recent changes caused an error if no flows were being plotted
Added ability for t2listing to handle overflow in AUTOUGH2 time step field- in which case the step property is set to -1
Bugfix in mulgrid optimize(): column areas weren't being updated
Added polygon_centroid() function to geometry module- this is now used to calculate column centres, and should give better results for columns with more than 4 sides.  Also modified polygon_area() function to work similarly
Merge branch 'fluxmatrix' into testing
Added connection_flows parameter to mulgrid layer_plot() method- to enable plotting flows through connections (rather than block-average fluxes)
Bugfix in t2grid calculate_connection_centres()- midpoint wasn't being calculated correctly
Added connection_flows parameter to mulgrid slice_plot() method
Updated documentation for new connection_flows parameter in mulgrid layer_plot() and slice_plot() methods