Make %context exec-dir inherited by further includes. #218

[chen-factual]

For #218. Ensures %includes in %context-ed scripts also inherit the context.

Example inclusion chain:

a.d context b.d include c.d contextd.d`.

The intended behavior is for b.d to use its own exec-dir, c.d to use the exec-dir of b.d, and d.d to use it's own exec-dir.

cc @potash if you can pull this branch and double check on your setup I'd be appreciative.

[potash]

Works for me! Thanks @chen-factual

[potash]

@chen-factual I think I spoke too soon. I think you somehow fixed the path that drake uses for subsequent %include and %context statements, but not the path used for step inputs and outputs. In fact it seems like %context is simple broken.

Here is a repo I made to test context. You should be able to run drake from either the top level or from the director dir but both fail for me on this branch.

Thanks in advance for your help with this! The %context feature will be very useful.