New convenient syntax for triangle and quad

[Bruce Sherwood]

The standard syntax for triangle and quad objects is this:

     triangle( v0=vertex, v1=vertex, v2=vertex, ....)

     quad( v0=vertex, v1=vertex, v2=vertex, v3=vertex, ....)

You can now alternatively write the following, which is sometimes more convenient, where "vs" is a list of vertex objects:

     triangle( vs=[vertex, vertex, vertex], ....)

     quad( vs=[vertex, vertex, vertex. vertex], ....)

Here is the relevant Help page:

     http://www.glowscript.org/docs/VPythonDocs/triangle.html