Shift start year

[ricardarosemann]

Shift the start year of when scenario assumptions become active to 2025; this is required for Remind Issue https://github.com/remindmodel/development_issues/issues/382

Two options are possible:

• Let mredgebuildings prepare all data until 2025: Use projections existing in mredgebuildings to generate data for the additional years, extrapolate all other data where necessary. This would require much less effort, but can be error-prone.
• Cleanly separate between mredgebuildings and edgebuildings: mredgebuildings gathers existing data, while edgebuildings includes all future projections. This would involve a more substantial refactoring of the code, but would provide a clean and more easily maintainable solution.

This issue applies to edgebuildings as well (Issue #15.)