Implement a sophisticated stdlib API

# A complete stdlib API
This pull request adds a complete, working and fully-usable stdlib API for complex usages. It features release management, retrieval of published releases and acceptance or rejection of suggested libraries for the stdlib.

It replaces the almost unusable current way where a lib either has the `default_include` attribute or not.

## Todo
### Release management
- [x] list releases (further testing necessary)
- [x] create release (further testing necessary)
- [ ] publish releases
- [ ] describe releases
- [x] delete unpublished releases (further testing necessary)
- [ ] modify unpublished releases
- [ ] modify unpublished release metadata

### more to come...

## Documentation
Alongside with development on this, the WIKI documentation is updated. See [here](https://github.com/maul-esel/ALD-API/wiki/Stdlib-API).