Simplified and standardized config file handling

[marcoheisig]

At the moment, the PiSCAT configuration files are placed in ../piscat_configuration, so in a location that depends on the current working directory. This should be changed to use the operating system specific standard locations (e.g. $HOME/.config on Linux).

Furthermore, I suggest placing all config data into a single toml file instead of multiple JSON files. Toml is easier to understand and modify by humans and well supported throughout the Python tool chain.

The only question we should discuss is whether we need to preserve backward compatibility with the old config files and their locations.

[po60nani]

It is not necessary to preserve backward compatibility. We only need to check CPU/GPU configuration can read this new version and initialize all variables in this class. It would be great to change the initial number of CPU cores from -1. This is fine when the CPU has 32 cores at maximum. But for more than this some os like windows 10 they show an error.