JBR API v0.0.8 - add GraphicsUtils

[AMPivovarov]

The first attempt was done in #188, and was declined.

https://youtrack.jetbrains.com/issue/JBR-5213/Allow-custom-Graphics2D-in-a-double-buffered-rendering-pipeline

[JB-Dmitry]

I'd propose to change the constraint-related methods in ConstrainableGraphics2 to be:

Rectangle2D getConstrainingRegion();
void constrain(Rectangle2D region);

This allows to get the dimensions of the constraining region, for symmetry, along with its location. And using floating-point coordinates will allow to add support for HiDPI cases in future, if needed, without extending the interface.

[JB-Dmitry]

Actually, using floating point coordinates only makes sense if coordinates are given in user space. sun.awt.ConstrainableGraphics's javadoc speaks about device space coordinates - for them integer coordinates should be fine.