Sorted Containers

Added sorted containers to DataStructures, testing, and documentation.
Replaced README.md with README.rst
Kevin,

Mostly the code uses isless, but at some point it needs isequal in order to answer queries like getkey and so on.  So I don't think it is possible to avoid isequal (but of course, it can be done by defining the default isequal_l(a,b) to be !isless(a,b)&&!isless(b,a) as the code does currently.)

With regard to using the ordering framework, I just looked at the file ordering.jl.  If I understand correctly, you are proposing is that the user of the containers provides an Ordering object instead of an isless function. Then my code should call 'lt' instead of 'isless;.  Does this mean that sorted dict should actually have three parameters, namely the Key type, the Value type, and the Ordering object?  (This is how it is done in C++, by the way.  In fact, in C++ there is a fourth parameter that serves as the memory allocator.)