Migrate MuonCollider changes and updates back to iLCSoft

[tmadlener]

BEGINRELEASENOTES

• Add the DDCaloDigi_BIB that has been implemented by the muon collider community for their studies and has been used for some studies there already
• Make it possible to do non-linearity corrections also for the ECAL in Pandora

ENDRELEASENOTES

Includes the changes in #28

@madbaron FYI, please add whoever should be added here for further discussion.

[madbaron]

Adding @sestini88, who I think is the author of DDCaloDigi_BIB (or might know who to add).

We might want to keep DDCaloDigi_BIB out of this PR.

It is definitely useful if we want to document historical/current studies, but the RealisticCaloDigi processors will generally be picked up by the community in going forward for SiW calos.

Dedicated work for crystal calorimetry is probably based on this processor and updates (Lorenzo certainly knows more than me here), so perhaps the processor could use a renaming to make it more discoverable. In the medium term, we should also figure out if there is any fundamental reason not to merge the crystal calorimeters work into RealisticCaloDigi instead.

[tmadlener]

I have moved the ECAL corrections into #28 which we can now probably merge a bit quicker