ozCore++: member init, storage clearing, ...

- ozCore
  * member initialisers where feasible => many classes are static-init-proof
    with default ctors
  * mReallocate
  * fixes of element initialisation in iterators
  * simd: vFirst() -> [0], equality ops & SIMD ctors moved to VectorBase
  * Thread::start() -> ctor
  * ShaderLib::open() -> ctor