Change the name of MenuOptionXXX Classes

[john32b]

I don't know why I chose this name way back then. It's not representative, and I don't like it 😞

I am thinking a more meaningful name ,such as MenuItem,
e.g.

MenuItemBase.hx
MenuItemToggle.hx
MenuItemSlider.hx
 ..

Also change the name of all the other helpers.
ItemData instead of OptionData
ItemStyle instead of OptionStyle
or even MItemData since ItemData feels too generic

[john32b]

Done, I did it on the last dev commit

• All elements that go inside a Menu are now called "MItems" instead of "Options" (Menu Items)
• All "MenuOption.." classes are now renamed to "MItem.."
• PageData and MItemData are now in djFlixel.gui.menu
• IListItem is now in djFlixel.gui.list
• Changes in function and variable naming in FlxMenu.hx, VListMenu.hx, Styles.hx, IListItem.hx, all MItem Types
• FlxMenu.callbacks_option -> callbacks_item. Also the string events have changed as well.
• "optChange" ,"optBlur" ... opt prefix removed -> "change", "blur", "fire"