Set defines for Doxygen

OTCrypto_OpenSSL and Lucre stuff was missing from the Doxygen docs.

Maybe not the best way to pass defines one-by-one but my CMake skills are
lacking here.
Move defines from stdafx.h to CMakeLists.txt
Merge pull request #235 from OttoAllmendinger/pr-doxygen-openssl

Set OT_CRYPTO_USING_OPENSSL for Doxygen