Better handling of deadline and timeout

[psi29a]

No description provided.

[psi29a]

In case anyone is wondering, pymongo never supported safe in drop and drop_collection... neither did we, it was just sucked up into **kwargs and ignored later on.
http://api.mongodb.org/python/current/api/pymongo/collection.html#pymongo.collection.Collection.drop

[IlyaSkriblovsky]

< grumbling >
Actually, I don't much like idea of adding some sort of hidden arguments to each query method.

This way it would be hard to write new method that would receive **kwargs and do something with it as with dict (like command() or distinct() create DB query from kwargs) without hidden knowledge that some sort of underscored arguments may appear in kwargs and needs to be removed aforehead.

Or if someone will introduce new query method and will fail to follow guideline of receiving **kwargs and mandatory passing it to all subcalls, the deadline feature will be broken. And this guideline isn't obvious from the code without studying internals of @timeout. This looks like a sign of fragile design that is easy to break.

You changes for supporting deadline is pretty broad already. Isn't it better to remove inlineCallbacks from query methods and get benefit from Twisted's builtin cancellation mechanism? This would be a massive change too, but it will allow us to keep deadline feature separate from internals of each query method.
</ grumbling >

sorry :)