AI improvement - using influence maps and A* better

[ledpup]

Units with little few movement points can often make poor movement decisions because they don't consider enough options. Instead of making a move decision based on the moves that can be made that turn, instead:

• Consider all hexes in a radius of 4-5 around the unit, ordering by highest influence
• Choose the best hex destination by selected the highest influence hex that is a possible destination (using A*)
• Choose the move based on what gets the unit the furthest along the route (plotted by A*)

[ledpup]

To find hexes in a radius, use:

[ledpup]

Done: method to discover the hexes within an area.

[ledpup]

Done: ordered influence maps + best possible destination TODO: unit move to best possible destination