Implement optional way of computing earnings using Irish FIFO rule

[pviotti]

FIFO rule.

It should not be implemented as default behavior since this is just a peculiar way Irish Revenue office has to compute earnings for taxation purposes, and it's not useful to DeGiro users in other countries.

[goenning]

I see that it currently has support for earlier/late period which is probably just an Irish thing. Is the intention of this tool to be a general purpose bookkeeping for all countries? Or will it be focused on the Irish specifics?

[pviotti]

Ideally this is going to be as generic as possible. Country-specific features will be optional (for instance, the --period parameter for Irish CGT can be omitted).