Builds produce two plugins

[gebner]

There are two plugin locations in a Pulse build:

1. ./build/ocaml/installed/lib/pulse/pulse.cmxs
2. ./out/lib/pulse/pulse.cmxs

(1) is created by make plugin and is used to build the library.

(2) is created by make and is used e.g. in the tests.

This leads to confusing situations where you've changed the pulse checker, it works just fine in the library, but you can't figure out why it doesn't work in the tests.

We should remove out. See also #508.