Change how often output data is written to files

[ubdbra001]

Currently the output data files are split into hourly chunks. This should be reassessed, maybe files should represent days.

If changing this then it would also likely be beneficial to increase how often the data is written to a file (so if there are issues the data already processed is not lost). Either write as the data is produced (but this may be too much I/O) or write hourly chunks to a single file per day?

[ubdbra001]

Code for splitting data into hourly chunks found in save_emission_rates_as_txt() within io_py.py

[ubdbra001]

Maybe saving should be incremental, but into a single file for each day? Perhaps saving every hour, or half hour, but also saving if it hits an error.

[ubdbra001]

To-do:

• [x] Move saving function to end of process_pair()
  • Save chunk of values immediately after calibration
  • Save single values from then on
• [x] Ensure that saving only happens once calibration has completed
• [x] Flatten dir/file structure for output

[ubdbra001]

Filename structure:

[date]_emissionrates[flowtype].csv

[twVolc]

Just to note that this links directly to #46, so once data are written iteratively I think both issues can be closed (just trying to declutter so that the number of issues isn't totally overwhelming).