Configuration files

Do not merge - this is a preliminary PR for discussion.

As of now, incorporates Dolphin's INI code for a configuration system. So far, handles for input controls have been added, but they haven't been hooked yet into the parts of code that use them. 
Please DRY. This adds at least `number_of_frontends - 1` redundant places to change code in whenever we want to add e.g. a hotkey to the configuration.