phobos commit, revision 1592


user: andrei

msg:
Added the existence of the property save as a condition for isForwardRange; added save to the range defined within; replaced a couple of awkward front() implementations; defined module-level moveFront() and range member moveFront() where appropriate; added @property maxLength to Take; arranged things such that take() for slice-able ranges returns the same type as the slice; eliminated SListRange; defined iota() with one argument; moved BinaryHeap within.

http://www.dsource.org/projects/phobos/changeset/1592