Clarify Java2D renderer is experimental / deprecated

[tillnagel]

As suggested, the documentation should mention that Unfolding for Java2D is not on par feature wise with the OpenGL-based renderers (including P2D).

[MrLoh]

Unfortunately the OpenGL renderer massively leaks memory in our library, this issue does not appear with the Java2D renderer, but only Open GL seems to be able to draw an overlay map. Do you have any idea what could be causing the memory leakage?

[tillnagel]

Which renderer are you using specifically? P2D, P3D or OPENGL?

[MrLoh]

I figured that the problem was caused by the resizability of the window, apparently OpenGL can't handle resize.

I was using the default renderer, I think that is P2D

[tillnagel]

Moved to new issue #107. Please specify or give code example over there.