Add ItemFlags for 1.8+

[MineTheCube]

Usage:

• Hide all flags: hideflags:true or hideflags:all
• Hide multiple flags: hideflags:flag1#flag2#...
• Hide one flag: hideflags:flag

Flags can be:

• HIDE_ATTRIBUTES, HIDE_DESTROYS, HIDE_ENCHANTS, HIDE_PLACED_ON, HIDE_POTION_EFFECTS, HIDE_UNBREAKABLE

Note that "hide" prefix isn't required, space are replaced by "" and text is converted to uppercase. So this will work: hideflags:placed on

[confuser]

Thanks very much @MineTheCube, will review shortly.