Fix foreign handlers API
Orangutan::Context has API for accessing, setting and managing foreign handlers... But they are called “manually” that is a developer needs to define handler and write special code for calling foreign handlers of the context. This looks like “hack”! I believe with foregn handlers defined the context can be (and even should be) without the handler. And the handler should be define only to overwrite the default handling of foreign handlers!
So we need to improve foreign handlers API so the context without the hander would be able to use foreign ones.