Add an option to differentiate similar initials

[arnaudgallou]

Currently, the initials for say Zip Zap and Zap Zop are the same (Z.Z.) in the contribution list.

I could implement a way to distinguish the initials of authors using multiple characters from their family name when the use of literal names is not an option. E.g., Zip Zap and Zap Zop could be initialised as Z.Za. and Z.Zo..