Module version of tool

Major updates are:
completed module setup
added database subcommand to manage db updates and also get summaries for different streams
added support for other ERA5 derived products and mars requests
requests can now be distributed across multiple users accounts
added new "urgent" flag to save priority requests in separate folder

First era5 download code release

First release, currently code is not yet working as a module.
Next step would be the module set up
To download era5 data from Copernicus Data services using son tables to select available variables and automate the process.