Save over 500KB with one weird trick

[ef4]

This PR cuts more than half a megabyte from any app that uses mirage.

The problem is that:

import _ from 'lodash';
let item = _(value);

needs to put methods on item for every possible thing lodash supports. Most of which aren't needed.

This isn't one of the cases where a more aggressive module bundler could try to optimize them out. This style really just can't be statically optimized. It's a pity, because the chaining style is easier to read IMO.

[samselikoff]

boss.