* make use of the return value for safety
* get rid of warnings
(sizeof(wchar_t) is the same as sizeof(u32), so no problem there)
* dynamic preview loading
fix crash when too many themes have previews available
What this commit adds:
* Ability to apply a theme, given a folder
* Extract all .zip files in /Themes/ into a relevant folder
* Get all theme metadata from info.smdh
* Proper unicode handling
What's still needed for initial release:
* Theme shuffling
* GUI