Added prototype to Tw2VariableStore
Added prototype to Tw2VariableStore

- Added `GetTw2ParameterType` @prototype which gets a Tw2 Parameter constructor from a supplied value
- This code already existed in the `RegisterVariable` @prototype but it couldn't be used without registering a variable (which may not be wanted)
- Added support for standard array values

`Tw2VariableParameters` could also be identified from a value but I'm not sure if this will cause issues anywhere without further testing
```
if (value.indexOf('.png') != -1 || value.indexOf('.cube') != -1)
        {
            return Tw2TextureParameter;
        }
        return Tw2VariableParameter;
```
ccpgames/ccpwgl,cppctamber/ccpwgl