Phobos addition formal review: std.experimental.allocator

[Dicebot via Digitalmars-d]

Small tip for reviewers: there are quite many modules in proposed 
package but majority is actual allocator implementation. I'd 
suggest to start investigating sources/documentation starting 
from 
http://erdani.com/d/phobos-prerelease/std_experimental_allocator.html 
and 
http://erdani.com/d/phobos-prerelease/std_experimental_allocator_building_blocks.html 
while using 
http://erdani.com/d/phobos-prerelease/std_experimental_allocator_showcase.html 
as reference for "highlight" examples.