clean-up of SSP-SDP scenario config. Deleted end-of-century budget runs and "plus" runs (extra sustainability settings in non-SDP runs)

fix in scenario config: start year 2025 for SSP1/SSP5/SDP-NDC scenarios, as these should be fixed to SSP2-NDC until 2020

bugfix 0935e7ee, reintroduced an if/else condition for a bound on biomass and renamed c_1stgen_phaseout into cm_1stgen_phaseout

This is part of a larger refactoring effort of the remind core. Here, code related to the trade of permits and primary energy carriers is moved from the core to the new module. Some renaming is required. For now only one module realization exists, 'standard', which corresponds exactly to what was in the core before. The results are not effected!