Misc

[pietern]

This PR is a bag of stuff I came across while moving functionality out of the root package into independent subpackages and moving all code to use a context.Context to make it easy to control client side timeouts on arbitrary sequences of requests. See: http://godoc.org/golang.org/x/net/context

Including:

• Move the event manager to a package (cc @daniellockard)
• Move the session manager to a package (cc @cgtexmex @hickeng)
• We were using url.URL as value instead of pointer value (unnatural if you look at the stdlib)
• Embed *soap.Client in root client
• Add keep alive soap.RoundTripper to session package (cc @hickeng)
• Move functionality to wait for a task to complete to task package
• Move managed object wrapper structs to object package
• Move property collector wrapper and functions to property package
• Wrapper functions in object package use context.Context
• Client in root package uses context.Context

[dougm]

Awesome @pietern , looks great! btw, feel free to remove '_gen' from the filenames, we can revisit that if we get a decent wrapper generator working.

[pietern]

@mkuzmin As a heads up, once this PR is merged it will break downstream code.

Wiring context.Context into the entire library was prompted by both your WaitForIP timeout problems and some code I had written that needed timeout management. Now that everything is wired up, every in flight chain of requests can be cancelled outside-in at any time. Through context.Context it is trivial to add timeouts to sequences of requests.