Add CMakeLists file for CMake build

[JaLooNz]

• Add CMakeLists file for CMake build for libraries and applications
• Various options are disabled instead of enable
• ECDH functionality will break self-test application

[rben-dev]

Hi @JaLooNz

Thanks for your interest in libecc and your PR!

I have small remarks before merging this:

• First, I cannot see the self tests binaries produced after cmake and make are called. Only the static libraries are built. I might have missed something?
• Also, as I can see the PLATFORM_WORD_SIZE is always set to 32, but the best option would be if it is not defined to let the library decide itself (as in the header a self detection is made to fit the compilation platform with the best size).

Thanks in advance,

[JaLooNz]

Hi,
CMakeLists updated to address the above issues.
Additionally, also fixed ECDH options due to missing source for executable.