Right now there are a couple ways to set the "usePowerOf2" user flag on a collection.
1) Create the collection. Then later call
2) At creation time, run
The latter is not very intuitive, since it relies on the user knowing how to interpret the "flags" bitmask.
We should allow a syntax like this:
and more generally, any option you can pass to "collMod" should also be something you can pass to "create".