Version 0.2

introduced failsafe strategies chaining mechanism;
agent-plug-hole distance based criterion performance dramatically enhanced;
agent execution frequency set from command line;
some visualisation improvements;
pause fix;
Floyd-Warshall test spec added;
see intended line of improvements in 'todo'.

** This is a squashed commit of the 'dev' branch, from 1a71ca22d3467c51639f853f8668dc31c3685910 to 4c59ef2c4ca12baddfd3bc000790e0d092912a5d