permit indirection in evaluation of integral constants in meta::, rbegin/rend/crbegin/crend
more doxygen work, add descriptive blurbs about views to the Users Guide
reorg readme, add pledgie, relocate n4128 stuff
work on swap and iter_swap customization points, zip view clean-up
workarounds for libstdc++ and libc++ on linux
Merge remote-tracking branch 'upstream/master'