Allow selection of games when uploading a replay

[jleclanche]

[beheh]

This is tricky - we need the HSReplay parser to provide user interaction, currently that side is completely decoupled from the UI. Maybe a few clever callbacks will do the trick.

[beheh]

Okay, and concerning parsing:

We do a preliminary pass through the file, searching for valid games, maybe extracting some basic metadata (like Player names). Then we fill the UI, and, after selecting the correct replay, we finally do the actual parsing.

[beheh]

Halting work on this right now. Will revisit later.