Aima4f - #480

Still a work in progress.

Still to be tested.

Simplify how classes that extend QueueSearchForActionsWrapper configure
themselves so its easier to do/understand.

To help reduce confusion it will instead provide a default
getNodeComparator() method.

These constructors indicate the default QueueSearchForActions
implementation that should be used in most cases (i.e. corresponds to
what is described in the book).

Move all queue based search algorithms into the 'extra' module.
Move all tests into the new 'test' module (so that 'core' and 'extra'
versions of algorithms can be tested together).

So the Hybrid Wumpus Agent can be moved back to core.

Ensure the locations linked to a location are not sorted by default.
This allows you to modify the order of linkage to test different
scenarios (e.g. trivial cycles).

Adds distribution and models for discrete Sample Spaces

Fix incorrect method call argument

Update to gradle 4.6

Update README.md for SENTENCE

Online-DFS-Agent - Clarify the need for the additional check if (!sPrime.equals(result.get(s, a))), which is not present in the pseudocode but required to stop it looping endlessly on certain test problems - and Added unit test for TableDrivenAgent in class TableDrivenAgentTest.java .

Add ConvertToCNF to readme.md of AIMA4e

Update .travis.yml to cache gradle dependencies

Add fig-7.? KnowledgeBase to readme.md

AIMA4e Search

Add DT-Agent in readme.md for AIMA4e