Draft: Ball and Stick Implementation

[zachcp]

• Initial implementation of Ball and Stick Rendering Style.
• Issue: pdbtbx does not currently process Bonds. So no way to iterate through them and draw them. There is, however, some work in progress
• Options:
  • implement bond discovery in this package
  • pull in bond discovery from an existing package: e.g. pymol / biojava / biopython
  • skip ball and stick for now.

I am going to skip this one for now as this was supposed to be the lowest hanging fruit.