External bindings

This PR contains the addition of external bindings in cOre according to [the documentation](http://rtfm.codeplex.com/wikipage?title=Bindings1&referringTitle=2nd%20Challenge). In order to speed up the process I have chosen to implement it only according to Per's idea and it seems to work ok. I've tried to write decent commit messages which should make it possible to follow my work through the documentation. I've also added all the examples from the docs to the repo in order to test the different features, all examples work correctly on this branch.

**N.B.** The PR is from `external-modules` to `lost-counter` since it contains some changes introduced in that branch, thus the `lost-counter` branch should be merged before this one.