[zefei]

Nice work! The pip/virtualenv loader is really great, and can make the plugin dev more purely focused on the plugin. I think this part can be a great standalone project.

But I don't know about the boilerplate functions, some of them feel useful (like output capturing, state preserving), while others are just shallow abstractions over the vim API, which is almost never good. Abstraction over API is only useful when it provides different and better semantics, like jQuery over DOM.