Add clearance detection and option in search method

[wibimaster]

Hi,

To move character bigger than 1x1 tile, I had to write a clearance detection. The clearance of each Node is stored at the Graph init, and we can use a "clearance" value in the search options. This script works for 2x2 tile for example, but isn't very accurate for 2x1 or 1x2 sized character.

Maybe someone can help me to optimize this a little more too ;)

[jorbascrumps]

Have you been able to improve accuracy on this, @wibimaster?