Prefixed all typenames with the library namespace.

This prevents clashes with identically named types in IECore. It also necessitated changing all the default names for newly created GraphComponents, and fixes various places in the bindings where it was assumed that the typename was the same as the python class name.

Fixes #330.
Improved GraphComponent::defaultName documentation.
Merge pull request #355 from johnhaddon/defaultNames

Prefixed all typenames with the library namespace.