S3 bucket listing support and network code refactors.

* Adds support for listing all objects in an S3 bucket.
* Renames a bunch of network related classes (Download->Action)
* Net actions now have static constructors
Fix problem with instance list not using the instance folder path
Valgrind-checked early application start
BLIND CODE, BLIND CODE HERE! WHERE IS THE COMPILER!?!?!

It choked on missing headers, maybe?
Add selectable message box helper, use it, make login GUI error label selectable