Load replays from url with web protocols

[VasilisThePikachu]

Extension of #136

Have a web protocol in a format somewhat like this

rtreplay://LINK-TO-REPLAY-DOWNLOAD.rtreplay (.rtreplay is just a renamed .zip that I plan to create in #136 to be able to just double-click the replay file to load it (and to help users not unzip it on accident))

This will just download the replay within the launcher and load it, preferably deleting it after the replay client process it closed. Just makes the replay loading process a little more "integrated"

This will though mean hosts may have to add special links to their replay download pages to support this.