- Don't fail re-registrations, just accept the last registration.
- Call a static version of aim_modules_init() in shared-library constructors.
  This is required to ensure we call the correct modules_init() function (the one relevant to our own librarie's code).
Merge into master from pull request #22:
Updates for use in shared libraries.  (https://github.com/floodlight/infra/pull/22)