Create panda3d_.py example

[cztomczak]

CEF 3 example externally maintained:
https://gist.github.com/croxis/9789973

Old CEF 1 example:
https://github.com/cztomczak/cefpython/blob/cefpython31/cefpython/cef1/windows/binaries/panda3d_.py

See also the Panda3D wiki page:
https://github.com/cztomczak/cefpython/wiki/Panda3D

[Moguri]

I created a cefpanda module (mostly based on Croxis' example) a while back for using cefpython in Panda3D and for trying to smooth over any pain points. I would be more than happy to help in this area.

[cztomczak]

@Moguri Sorry for late response, I missed your post. Pull requests are welcome, however requirements for the code are strict before example can be accepted into the examples/ directory, so it usually requires much work.

Another Panda3D integration example:
https://github.com/thetestgame/PandaChromium