added x and y parameters to hello world example for helpless newbies like me :)
Faster implementation for dropping nodes in big graphs.
Fixing GEXF parsing in IE.

IE apparently doesn't support getElementsByTagNameNS for XML documents.
if edge weight is set, set size attribute to this value to make setting minEdgeSize and maxEdgeSize effective
Merge pull request #44 from edsu/master

x and y in hello world example
Merge branch 'faster-drop-node' of https://github.com/tjdett/sigma.js into tjdett-faster-drop-node

* 'faster-drop-node' of https://github.com/tjdett/sigma.js:
  Faster implementation for dropping nodes in big graphs.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'fix-ie-gexf/fix-ie-gexf' into devel