synfuel update

Created by: fschreyer

This fixes synfuels to zero in baseline runs and moves the minmial lower bounds of synfuel technologies to after 2030 (avoids infeasibilities in certain cases). Also, a switch to force in synthetic gas was added in analogy to the one for synthetic liquids. These switches now force in synfuels starting in 2035 (more realistic than from 2025 onwards after discussion with industry guy from Sunfire).