(Fixed) More XML settings for iOS and Android, mouse wheel cheat code 

*(I closed my previous conflicted pull request)*

**This seems a bit weird. Icons are allowed for every target (admittedly, they don't really do anything for neko and flash). Also, .png is not the only allowed format.**

Some games can't make use of vector graphics on icons (generated from SVG), and on iOS and Android there are so many icons and launch images to include, it's very handy to have them here. In this case, PNG is the only format allowed.

**I'm getting different values (3 and -3).**
Fixed that.

**FlxSignal**
I didn't write that section, but I will take a look on what you mentioned.

@Gama11. If there's any detail I missed, let me know.