added Grid and AStar usage test
Squashed 'external/algorithms/' changes from 62252c0..e20e8c2

e20e8c2 Merge branch 'fix_empty_result_astar' into develop_patched
73bb385 Always returns start and end nodes when a path is found in astar

git-subtree-dir: external/algorithms
git-subtree-split: e20e8c229a94c1959331272fce8375ee83037130
merge last algorithms commits