Force used to applyImpulse is now scaled with mass

In Oimo, the mass is not directly set. The force used to move this object should be scaled by the mass of the object.
Adjusted type of shaderPath in shaderMaterial so it is the same type as baseName in "engine.createEffect()".
Merge pull request #280 from Temechon/patch-14

Force used to applyImpulse is now scaled with mass
Merge pull request #281 from daner/shader-patch

Adjusted type of shaderPath in shaderMaterial.
Adding effect for particles