Adding layers and rendering scale

[ashish2199]

Changes

Addition of the concept of layer

• Layering works by sorting the list of entities to be drawn based on the layer.( created a new layerComparator for this )
• Player is rendered at layer 0
• Anything to be rendered below the player will get layer < 0 i.e Negative
• Anything to be rendered above the player will get layer > 0 i.e Positive

Addition of the concept of scale