Previously forecast offset `df_scenario` was computed only when number of scenarios was
greater than one. Long-term scenario data should use a special label in the `f` dimension
in all cases.

Re-implementing dynamic generation portfolios (see issue #119). Unit investment variables still have the 't' dimension, although it is kind of redundant. Units have technical lifetimes (given in ut set) but links are assumed to stay in the system forever after they have been built. Cost discounting and multi-year horizons are considered in the objective function but not in the results outputting yet.

First working commit for the new inputs and outputs system. Probably buggy... In Google Drive there is 8unit system excel that works with this (vInputOutput.xlsx).

Set `gn_forecasts(*, node, timeseries)` tells for which grid/flow/restype, node and timeseries combinations use forecasts and by default includes everything.

See: #99

First try to fix issue #97.

Changed behaviour of `mSetting` 't_perfectForesight' so that it’s defined from zero (not after 't_jump')

The setting does not have any effect if 't_perfectForesight' is less than 't_jump'.

New model setting `t_perfectForesight` gives number of time steps after `t_jump` where realization foreast is used

Also added some default values to scheduleInit_temp.gms

Making it possible to choose in the modelsInit.gms file whether to include the two additional incremental heat rate equations that use binary variables:
- mSettings(m, 'incHRAdditionalConstraints') = 0: use the constraints but only for units with non-convex fuel use
- mSettings(m, 'incHRAdditionalConstraints') = 1: use the constraints for all units represented using incremental heat rates
Enabling incremental heat rates also in the invest model (and potentially in the building model). Some clean-up to the incremental heat rate equations.

Issue #55: Commented the 'ts_effUnit' and 'ts_effGroupUnit' out for the time being, as their implementation is not clear.

Adding an option for linear improvement of the central forecast toward the realization, controlled by 'mSettings(mType, 't_improveForecast)' instead of the old 'f_improve' parameter. Also added readiness for updating only existing values when updating forecasts (currently commented out), as well as removed some old unused code.

Issue #50: Changed the 'mStart' values in the model definition file templates to avoid errors with the simulation start time.

Changing results_t_start to t_initializationPeriod (=the number of time steps in the beginning of the simulation that are solved but not included in the results) and t_omitTrajectories to t_trajectoryHorizon (the number of time steps when start-up and shutdown trajectory constraints are 'active' in the beginning of each solution).

Reserve length is now a node property instead of a model property. In addition each reserve category can be turned on or off in the model settings.

Aggregation of units now handled by unitUnitEffLevel in inputData instead of 't_aggregate' in mSettings. Allows to choose aggregation threshold by unitAggregate and links it with the efficiency levels (and probably avoids issues since it was previously possible to have different horizons for aggregation and efficiency levels). Addresses issue #22.

Also bug fix to v_onlineMIP to v_onlineLP transfer where v_online was active for both at the t just before the switch.

Aggregation of units now handled by unitUnitEffLevel in inputData instead of 't_aggregate' in mSettings. Allows to choose aggregation threshold by unitAggregate and links it with the efficiency levels (and probably avoids issues since it was previously possible to have different horizons for aggregation and efficiency levels).

Also bug fix to v_onlineMIP to v_onlineLP transfer where v_online was active for both at the t just before the switch.

Updated some terminology and changed the effLevel determination from start time step to end time step. Addresses issue #19.

Enable the use of advanced basis. Three options: use the latest solve, use all solves from the previous run, use the first solve from the previous run.

Also changing the length of the forecast horizon so that it is now possible to either keep a static length for the forecasts or to have a decreasing forecast horizon that only extends forward at every tForecastJump.

Model definition files included in the VCS now only include the GAMS definition (list of included equations), all of which are read by Backbone to allow for easier swapping of models without having to tamper with the "3e_solve.gms" fole. Rest of model parameters are expected to be given as input through the renamed "modelsInit.gms" in the input folder (by default). "periodicLoop.gms" and "periodicInit.gms" now treated as integral parts of the Backbone model.

Example input parameters provided by the "scheduleInit_temp.gms", "buildingInit_temp.gms" and "investInit_temp.gms" included in the defModels folder within the VCS.