- Move some RenderCore specific classes and all shaders into RenderCore source tree.

- Implement all existing Three.js functionality with RenderCore.

- In RenderCore, further improve on existing functionality:
  - Textured points - arbitrary size and shape.
  - Mesh lines - arbitrary thickness.
  - Object and sub-object picking through color buffer with fragment depth detection.
  - Camera handling like in TEve, with ability to pick rotation center.

C++ / Server Changes

- REveManager: Make RenderCore the default rendering engine.

- Stream interpreter errors and show them in client log

- Add flag fIsRCore to REveManager.

- Make REvePointSet secondary-selectable.

- Add parameter for projection depth in REveDataCollection

JS / Client Changes

- Remove error MessageBox popup during client updates.

- EveManager.js: Check change bits in ImportSceneBinary when scene changes are streamed.

- EveScene.js: Optimize visibility changes.

- EveScene.js: pass eve_element instead of object3d in cases
  where it simplifies the code.

- EveScene.js, GlViewer classes: Cleamup highlite/selection management so it
  can be abstracted for RCore.

- Separate viewer-side selection processing for Three / RCore.

Tutorials / Demos Changes

- event_demo.C: secondary select points, jet title include pT.

- Tune marker sizes, colors, visual parameters.