Added support for compartments.
Added support for compartments.
Added gpr parsing, QP solve method, MOMA, gene/reaction deletion and essentiality.

Warning: analysis.fba renamed to analysis.simulation, Solver.build_lp
renamed to Solver.build_problem, FVA moved to analysis.variability.
Gurobi output is now silent.
Solution values changed to dictionaries; Solution status more meaningful.
Updated both solver wrappers (removed unsafe dependency from model).
Merge branch 'master' into kai-branch
minor spacing changes