Fix for #7260: PointLight shadows work properly only if shadow is applied to first light added to the scene.

Quick docs fix for Matrix4.makeOrthographic.

Added call to _renderer.resetGLState() at the end of light loop in WebGLShadowMap.render(), updated WebGLRenderer.refreshUniformsShadow() to send inverse of point light position to shader. Fixes #7260.

WebRenderTarget refactoring: Use Texture instance

Removed loadAjaxJSON-section