Django nodes cache

[iurisilvio]

It is really slow to parse templates everytime you call render_block and it is a static information, so you can cache it in memory.

I did some benchmarking here and this node cache improved performance ~20%.

Most part of the work was done by @walison17, I just wrote a test and did the benckmark.

[clokep]

Looks like this needs black run against it for formatting! 👍

[iurisilvio]

Yes, I ran black and fixed the formatting.

[iurisilvio]

I added a commit here to support anonymous templates. It is a case where template.name is None, so it was clashing cache keys.