efficient input range buffering

[Martin Nowak]

I've written a wrapper to promote input ranges to buffered forward ranges.
It allows to write range agnostic lexers/parsers with infinite lookahead.

Buffering is done through a singly linked list of memory blocks that are  
reference counted.
Each saved range holds a reference to all future blocks.
Blocks are recycled when being no longer used.

https://gist.github.com/1257196

There is a major issue with the somewhat broken implicit-save-through-copy  
concept.
A lot of copies in function parameters, foreach loops etc. will also create
references and thus can be easily responsible for inefficiencies.

martin