Added drawcalls example for buffergeometry

I've created an example of using ```drawcalls```on ```buffergeometry```to dynamically modify the number of points and lines to paint.
It's used both on a lines set and a pointcloud.

You can see here the working example:
http://kile.stravaganza.org/lab/js/examples/webgl_buffergeometry_drawcalls.html
Do you mind converting all the indentation to tabs?