Fix Old Material Library (anoying missing mrMaterialAttribs.gup popup message)

This simple function will remove any missing Mental Ray attributes from material and
save it as new library.

fn fixMtlLib mlib_Path: suffix: =
(
	if not doesFileExist mlib_Path then messagebox "This Material Library not exists!" title:"Warrning" beep:off else
	(
		with redraw off
		(
			local mlpath = getFilenamePath mlib_Path, mlname = getFilenameFile mlib_Path, new_ml = mlpath + mlname + suffix + ".mat"
			local missingLegacyAssetsNames = #("mental ray: material custom attribute"), newLib = materialLibrary()
			local tempLib = loadTempMaterialLibrary mlib_Path
			local arr = (for i = 1 to tempLib.count collect (s = sphere() ; s.material = tempLib[i] ; s)) --; select arr
			SceneConverter.RemoveMissingLegacyAssetsFromScene missingLegacyAssetsNames
			for i = 1 to arr.count do append newLib arr[i].material ; delete arr
			saveTempMaterialLibrary newLib new_ml
		)
	)
)
-- example - this is my old VRay CarPaint library. 
-- use diferent file path and add suffix just to avoid any override
fixMtlLib mlib_Path:@"d:\grayroom\GR_Materials\CarPaints.mat" suffix:"_FIX"