(feature) re-parametrized splitting to 1/k0 terms

[jspaezp]

As we discussed, this changes how the 'uniform' splitting method works to make the definition be in terms of mobility instead of scans.

The change requires passing around a reference to a scan to im converter.

In addition there is a minor refactor to pass a reference to SqlReader instead of passing a path that then will be used to read another SqlReader (which might save a couple of ms here and there).

LMK what you think! happy to make any changes needed.

[sander-willems-bruker]

Thanks for the good work! At a quick glance most looks like I'd expect it to (haven't run the code just yet). Few comments I already can make before testing locally:

• I changed base to develop, this way you avoid merge conflicts and I can handle them on my end if needed.
• Currently a panic occurs if there is no converter while required. I probably want to change that to error propagation rather than a panic.
• I would like to have the choice to use either scan indices or im values. I.e. add your work to existing code base rather than replace the scan option

[jspaezp]

@sander-willems-bruker I believe its good to go, LMK what you think.

[sander-willems-bruker]

Merged into develop via #27