Downloading route content (Github, zip)

[sweiland-openrails]

Trello card

I've created within the Main menu a separate window "Download Content". So that it can be enlarged when more download options would to be added (trains, consists, etc.). Just like the Resume/Replay.

Wishes for the second phase:

• add uninstall button
• add info button, starts webpage
• replace hardcoded GitHub URL's by downloading a file with it from GitHub Open Rails
• add check for diskspace and tell how much diskspace is used by the download. "Download" might not be the right verb, "Install" to be used?
• progress bar, there is no such thing as a callback for every MB downloaded from the repository Clone. I might be able to get the total amount Mb to be downloaded versus the already downloaded MB in a progress bar. And have the download process running in a different thread.
• load the just downloaded route in the menu as the to be started route. Or even start the route.
• add a update button and beforehand show what's get updated.