Port HashedString32

[MakoEnergy]

Port over the HashedString32 class and its tests from the monolithic repo.

https://github.com/BlackToppStudios/Mezzanine/blob/master/Mezzanine/src/hashedstring.h
https://github.com/BlackToppStudios/Mezzanine/blob/master/Mezzanine/src/hashedstring.cpp
https://github.com/BlackToppStudios/Mezzanine/blob/master/UnitTests/tests/hashedstringtests.h

This was originally written pre-c++11, prior to the existence of std::hash. This may or may not be worthwhile for us to use, as the actual hashing algorithm is implementation defined (as long as it meets certain standardized criteria). So we should evaluate if we want the the std implementation, interface, or none. In the event we decide to port our own hashing implementation these files should be used:

https://github.com/BlackToppStudios/Mezzanine/blob/master/Mezzanine/src/Internal/murmurhash3.h.cpp
https://github.com/BlackToppStudios/Mezzanine/blob/master/Mezzanine/src/Internal/murmurhash3.cpp

[MakoEnergy]

Also, this issue is relevant: BlackToppStudios/Mezzanine#113

Edit: Since we're using C++17 now, HashedStringView?

[MakoEnergy]

As of commit c690896 the Murmur hash functions from the monolith repo have been ported, getting one step closer to completing this.