Make parse compatible with CSP

[vrana]

Using parseRows with CSP enabled is quite cumbersome. I don't see a reason why this shouldn't just work (even though a little slower).

[koto]

Is there any reason not to merge it? This allows d3 to work on applications that use CSP without unsafe-eval, which seems quite beneficial. The less-performant branch is only taken if the new Function has failed due to CSP.

[vrana]

I've added a test and fixed the formatting.

[curran]

Just curious, how much slower is this?

[zzacharo]

Hey, any update on this? It would be really helpful for us as it would allow us to apply proper CSP while still using this library.