"Smart" extract

[gillchristian]

The current version of the extract is very naive. It runs the extract CLI (meant to extract only one module at a time) in parallel in each directory of DefinitelyTyped. Since each module takes between 10-20s, running it in my machine (one module at a time per core, 8 cores) takes ~4hs for only DefinitelyTyped.

That is only necessary for the first time. After that we extract only the modules that changed (that also applies for the whitelist #13).

There are a few options for DT:

• Nightly update the repository (DT) and extract the types of the modules that changed.
• Add a hook to DT repository (would require contacting maintainers) and update types from the changes to the repository.

For the whitelist:

• Clone the whitelist in a machine (mine?) and nightly update repos and types that changed.
• Use npm hooks to listen to new version of these packages (if there's such thing) to update types of those packages.
• Have a mirror of npm with on only the whitelist and DT packages and keep have hooks to that for new packages versions. This seems like an overkill and if we ever do something like this is way down the road.