Keep std::deque algos specializations in Debug mode

[François Dumont]

The last optimizations that get disabled when Debug mode is enable are 
the algo specializations for std::deque iterators.

This patch move those algos in std namespace as they should even when 
Debug mode is enable so that they get considered even when calls are 
made with the namespace qualification. And it adds all the algos Debug 
implementations which forward to normal implementations to benefit from 
optimizations.

Note that I try to use typename deque<>::iterator or typename 
deque<>::const_iterator to define Debug algos but it didn't work, gcc 
was just not considering those overloads. I wonder why ?

I added test and manually checked that behavior was correct. Do you see 
a way to automate this validation ?

François

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