Desmod

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* [NEW] Add sim.vcd.start_time and sim.vcd.stop_time
* [NEW] Add unit tests for desmod.tracer
* [NEW] Dump configuration to file in workspace
* [NEW] Add unit tests for desmod.dot
* [FIX] Use component scope instead of id() for DOT nodes
* [NEW] Colored component hierarchy in DOT
* [FIX] Repair typo in fuzzy_match() exception

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* [CHANGE] Overhaul progress display
* [NEW] Flexible control of simulation stop criteria
* [FIX] Support progress notification on spawned processes
* [FIX] Remove dead path in test_simulation.py
* [FIX] Various doc repairs to SimEnvironment
* [CHANGE] Add t parameter to SimEnvironment.time()
* [CHANGE Parse unit in SimEnvironment.time()
* [NEW] Add desmod.config.fuzzy_match()
* [REMOVE] Remove desmod.config.short_special()
* [NEW] Add coveralls to travis test suite
* [NEW] Add flush() to tracing subsystem
* [CHANGE] Do not use tox with travis
* [NEW] Add Python 3.6 support in travis
* [FIX] Repair gas_station.py for Python 2

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* [CHANGE] simulate_factors() now has factors parameter
* [NEW] simulate() can suppress exceptions
* [FIX] simulate_factors() respects sim.workspace.overwrite
* [CHANGE] Update config with missing defaults at runtime

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* [NEW] Add env.time() and 'sim.now' result
* [FIX] Enter workspace directory before instantiating env
* [CHANGE] Use yaml.safe_dump()
* [FIX] Add dist to .gitignore
* [FIX] Squash warning in setup.cfg

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* [NEW] Add Queue.size and Queue.remaining properties (9)
* [NEW] Trace Queue's remaining capacity (10)
* [NEW] Add Queue.when_new() event (11)

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* [NEW] Add desmod.simulation.simulate_many()
* [FIX] Repair various docstring typos
* [FIX] Disable progress bar for simulate_factors() on Windows
* [NEW] Add CHANGELOG.txt to long description in setup.py