Potential fix for 'import' bug

In Python 2.7, adding

    from vapory import *

to a .py file will overwrite the value of `__name__` for that file, setting it to `"vapory"`.
This breaks the common `if __name__ == "__main__":` idiom.

I'd suggest that it's better that `from vapory import *` imports *everything* like you'd expect (and doesn't try to hide implementation stuff like `wikiref` and `format_if_necessary`). That's what this fix does.

Alternatively, have it just import the contents of vapory.py, and move anything that's not wanted in the public interface to a different file. I've kinda done this too - I think it makes the code a bit neater.

There are a few other changes in here too that I noticed while looking at the code.

* added a classmethod for class name transformation (the code for this was copy-pasted twice before)
* whitespace fixes
* Blob and Prism classes added