[A] PD: Parse output section; Add output_file_prefix.
[PL] Pass output stream to Process::post().
[PL] GW: Add output in post().
Merge pull request #533 from endJunction/bc

Dirichlet boundary condition for GroundwaterFlowProcess.
Merge pull request #534 from endJunction/SimulationOutput

Simulation output
Merge branch 'test-improvements' into develop
[BL] Start CPUTime and RunTime timers at creation.
[PL] GW: Time solve().
[ML] Change LIS's linear solver default tolerance to 1e-16.
Timing and memory scripts.
Enable diff tester for the quad_20x10_GW benchmark.
[B] Change output file name in quad_20x10_GW.prj
Logog level ALL.
Add cube and square benchmarks for GW.