[OptiFine JEM] Add warnings for invalid per face UV values

[ewanhowell5195]

Detailed description of your suggestion

In an OptiFine, per face UV must follow these rules:

• UV sizes cannot be smaller than 1 or larger than -1 (so 0.5 and -0.5 are not allowed) 0 is allowed however
• UV offsets MUST be whole numbers

in the above example here, every value breaks the rules

in the above example, only the first two values break the rules

If these values break the rules, the entity model's textures will render unexpectedly and/or look completely broken

Please add the warnings system to the OptiFine JEM format to alert people when they are making invalid models