clean up some other code

cleaned up a bit the luminosity function notebooks

shows:
current grid status (#/# and modulo)
estimate of time remaining and time to finish
memory use (of all processes)
time per run

Integrated the new functions, population_id will now be renewed upon running a grid, prevented evolve_single from running if there are no arguments passed, added some check in the export_all_info function that raises an error if the user tries to export without outfile OR data_dir

add methods to grid.py:

rename_grid_variable
update_grid_variable
clean

add functions to functions.py:

convfloat
datalinedict
pad_output_distribution