Add google analytics tracking to Python and Java bindings

[tschoonj]

Events will get sent once when the modules are loaded, and this will happen in a separate thread that will terminate afterwards.

[kalvdans]

Why? No one likes being tracked.

[tschoonj]

I like having a rough idea of how many people use my software and where they are from (approximately): this gives me some justification and the necessary drive to continue working on it and making new releases, especially since I do this mostly during weekends and holidays, as I am no longer involved with X-ray physics professionally.

I will consider adding an opt-out flag to avoid tracking, using an environment variable or so.

[tschoonj]

Google Analytics support was removed in #235, as Google removed the Universal Analytics some time ago, and any events sent were no longer being processed.