new-iter-concepts

This document proposes a new system of iterator concepts that separates access and positioning requirements. This allows concepts to better match algorithm requirements and categorize real-world iterators. Key points: - Current concepts mix access and positioning, limiting accurate categorization of useful iterators. - New concepts include Readable, Writable, Swappable, Lvalue for access and Incrementable, Single Pass, Forward, Bidirectional, Random Access for positioning. - This is backward compatible and extends the standard in TR1. Future papers could update algorithms and deprecate old concepts.