Optimise RegExp.replace().

Optimise RegExp.remove() [drop is_string() check].

Optimise Iter & SplitIter, drop SplitIter.withOptions().

Fix Iter.getNext(),getNextEntry(),

  add getNextPair(),key(),value(),
  optimise.

Drop Type.isRegExp().

Update format() [add %T spec],

    add Type.isInstanceOf(),
    optimise XClass.isClassOf(),
    doc-ups.

Add XString.xslug() method.

Doc-ups.

Fix get_path_info() [lower extension issue].

Add Arrays.take(),XArray.take(),array_take() stuff.