Teach pyflakes about simplates

[Changaco]

To prevent all the errors that pyflakes detects, such as undefined variables. This is potentially a hard thing to implement though.

[chadwhitacre]

Undefined variables could be dealt with in #30.

Otherwise this should be ticketed over in PyFlakes, no?

[Changaco]

Undefined variables could be dealt with in #30.

#30 is primarily about implicit versus explicit, the latter would make it easier to detect undefined variables, but actually implementing that (via pyflakes or otherwise) is a separate issue.

Otherwise this should be ticketed over in PyFlakes, no?

Yes, but I think it also belongs here (actually, in the soon-to-be simplates.py repo), because if it's only ticketed in pyflakes then someone looking to contribute to aspen won't know about it.

[chadwhitacre]

Okay, labeling this one Core so it gets moved out to the core repo once we have that.

[chadwhitacre]

(thence to simplates.py)