Create `Plot.attr` as an alias to `Plot.project`
No other functionality in the library changed. Non-breaking change.
I updated the quicktests to use `.attr` both to demonstrate that it works
and because I think this will be the standard way of calling the API going forward.

Close #794
Add a single whitespace
Merge pull request #1024 from palantir/project-alias-to-attr

Create `Plot.attr` as an alias to `Plot.project`