Splosh now reads sink files; many changes. Added units for sink mass. Added a 'get_unit' function to menu_units; tidied up plots.py using this.
Added some mks conversions in data. Added routines to read sink data in pymses_wrapper. Added option to show sinks (or not). Added code in plots
to deal with sinks and unit conversions. Added code in mpl_base_backend to write sink data to the screen. Basically did everything required to
add sinks to rendered plots except the actual plotting bit.