added diagonal cost
switched parameters
Merge branch 'master' of https://github.com/DanielSt/javascript-astar
use options parameter instead of parameter list.  Issue #12 and Issue #16
remove old test file
prep for 0.2.0
Closest implementation, with relevant update to demo page and initial test.
remove closestHeuristic
remove superfluous code from closest
function formatting
slightly better tests for closest option
whitespace
use 1 and Math.sqrt(2) for costStraight and costDiagonal, rather than allowing options to be passed in. Issue #12
Fixes #19
Fix if check to account for non node people
Ability to have non-grid layouts

- Extract grid specificities into the Graph function
(thus replace `grid` parameter to a `graph`object)
- Regroup heuristics functions under astar.heuristics
- Update tests, benchmark & demo
- Added a specific test to demonstrate non-grid layout usage with a gps
heuristic
Remove useless comment
Remove useless local variables in Graph constructor
Rename GraphNode to GridNode because only used in grid mode
Move gps heuristic function to tests.js

Also clearer segmentation between heuristic function and cost function.