Revert "update LineGraph2DRenderer to use GraphBuffer to draw line. Combine Labels and axis."

This reverts commit 831b9cd88313cc0340cb289dcc1a3cec7cabb5a5.

Conflicts:
	graphene/src/main/java/org/epics/graphene/GraphBuffer.java
	graphene/src/main/java/org/epics/graphene/LineGraph2DRenderer.java