[SPORK-114] Move ordering refactor + composite move ordering

[KYLChiu]

See the linked issue #114 for motivation.

• Refactor move ordering for readability.
• Removes circular dependencies between killer moves and searcher, now searcher owns the killer table.
• Adds simple composite move ordering class, combining killer moves and MVV-LVA.

[KYLChiu]

I am keen to change the design, hence stopped reviewing in details. We briefly discussed before using a factory pattern but dropped the idea since we both didn't quite understand it. Want to pick up that discussion again.

You implemented SearcherFactory though! ;) maybe it's the essence of programming that we don't understand but somehow stuff works. Anyway, replied to all

[ccjeremylo]

I am keen to change the design, hence stopped reviewing in details. We briefly discussed before using a factory pattern but dropped the idea since we both didn't quite understand it. Want to pick up that discussion again.

You implemented SearcherFactory though! ;) maybe it's the essence of programming that we don't understand but somehow stuff works. Anyway, replied to all

Sorry I meant decorator - not factory!