medium.Core is on describing
threejs libray is added.
core file renamed 'core' from 'medium'.
basic gitignore is set.
 - eclipse project setting files are not going to be tracked.
Merge branch 'test/three.js' into jy
the way to use a namespace is changed.
 - now this code is available -> mynamespace.inner;
namespace bug fixed.
 - it did not work.
 - because it tried to find a namespace in window.namespace, but the namespace exists in window object.
namespace bug is fixed
 - it did not work at all before
core skeleton code is set up
 - medium.graphics.Graphics
 - medium.graphics.Scene
 - medium.net.Client
 - medium.Physics
cannon js is included
basic natural assets are added.
 - grass, plywood, rocks, wood
graphics class is replaced by cannon library
oop library is replaced by js.class
Babylon is added, and replaces cannon.
 - Babylon is 3d engine including cannon.
medium.net.client using restful api is roughly done.