Add Test namespace within CryptoPP namespace

[noloader]

On occasion users will ask about missing symbols in the library, like GlobalRNG(). It has come up on several occasions, including Stack Overflow and the User Group.

The problem appears to stem from creating a project with an external build system (like CodeBlocks, Eclipse or Xcode), and adding all the header and source files to the project. On our side, its not readily apparent a symbol like GlobalRNG() is part of Testing and Evaluation.

At this point, we are going to keep the code in regtest.cpp out of Test::. The functions are used for an object registry, and they are useful to the library and testing. In the future, we will make more use of it when the Engine like interface gets cut-in.

This bug report tracks the addition of a Test:: namespace within CryptoPP:: namespace.

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Adding the namespace is just maintenance work. There's no thinking required. At the same time, we will pull GCC's deprecated warning suppression (no longer needed), and USING_NAMESPACE(std) (no longer needed for most files). Its more mindless work.

[noloader]

Also see Commit 73836e58a5f5c11c and Test namespace within CryptoPP namespace on the mailing list.