New Commands implementation.
Commands: Allow parallel execution of newSutInstance
When testing, set the Future thread pool size to Test.Parameters.workers, instead of using default number of threads.
Add Commands example that uses NixOS and libvirt
examples/commands-nix: Add gitignore
Add initial Commands LevelDB example specification
CommandsLevelDB example: Add Open and Close commands.
Commands.canCreateNewSut now takes both initialising and running SUTs as arguments
Wrap Command.run in Try. Fix bug in SUT creation/deletion.
commands-leveldb example: Remove preconditions
Add Commands.UnitCommand
commands-leveldb example: Add commands for get/put
commands-leveldb example: Precondition on Open
Commands: Fix tests, and add SuccessCommand
scaladoc fixes
Remove old Commands implementation
Fix scalac -feature warnings