Fix broken behavior in case of texcoords mapping (we do need texcoords node in all cases, then, even for UV coords...). Use nodes by default when generating new write-allowed wrapper around a material. Do not try to find nodes in existing tree all the time, do it only once, even for lazy-initialized nodes (through accessors). Fix ugly spacing in property accessors (since it looks like some people do not like a single 'block' with both getters, setters and prop definition, at least use one sep line everywhere (and two sep lines to separate properties)...