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.
refactor #21 to include getCost(), make a separate graph type for cities, and document the new search interface
prep for 0.3.0
Rename GridNode .type property to .weight
Efficient Graph.prototype.toString

- Optimize with .join rather than lots of string concatenations
- Add comment to specify that .toString() only work in grid layout mode
Use Performance API if available

Performance API is more precise
https://developer.mozilla.org/en-US/docs/Web/API/Performance

http://updates.html5rocks.com/2012/08/When-milliseconds-are-not-enough-performance-now

Note: I did not switch new Date().getTime() to Date.now() because it
only works with IE>8.
But this might be interesting because Date.now() is faster than new
Date().getTime() (no object creation).

http://stackoverflow.com/questions/12517359/performance-date-now-vs-date-gettime
Move pathTo function outside astar.search

This small optimization avoid to redefine the pathTo function in memory
each time astar.search() is called.
update comment for issue #21
Merge branch 'master' of https://github.com/TiTi/javascript-astar
Code formatting
- Only use one var when possible
- Define one var on each line (child1N)
- Avoid comments on 2 lines for a few chars
- Remove unecessary empty lines
Remove extra spaces
Fix jshint var is already defined
Untabify demo.js

No code change. Only replace tabulations. Thx Notepad2
demo.js code formatting

Ability to put breakpoints into setTimeout functions
Fix jshint warnings in demo.js
Refactor drawDebugInfo
Fix .cost vs .getCost()