Various fixes for discretionary_policy
- Saves planner objective and closes #1041 (closed)
- Adds unit test for correctness of results
- Fixes updating of lead_lag_indicidence
- Evaluates Jacobian at steady state of model (makes it compatible with histval and initval)
- Disallows mod-files with number of instruments not matching number of missing equations
Related to #1045 (closed)
TBD: fix preprocessor error in unit test (email to Houtan from 08/30/15)