CMake build system initial implementation

[uael]

Proposal #5 Related #8 #11 Just an overview of what could be the build system implementation.

[uael]

Let me known what do you think about this implemetation. Done/missing list:

• [X] configuration
  • [X] 32 bits
  • [X] FPENV
  • [X] valgrind
  • [X] address sanitizer
  • [X] coverage
• [X] debug/release
• [X] config header ready
• [X] MSVC ready
• [X] static/shared lib
• [X] versioning
• [X] installation (make install)
• [ ] packaging (cpack)
• [ ] tests
  • [x] success tests
  • [ ] fail tests
• [X] bench
• [ ] travis update
  • [X] platform/compiler matrix
  • [ ] configuration matrix (commented)
  • [ ] OSX ready (commented)

[hnes]

Thank you very much for your nice contribution, @uael :D

The OSX support has just been added to the master branch of libaco and would be released with the next v1.2.3. I have merged some part of the .travis.yml from this PR into the master branch. Thank you so much for your contribution :D

Unfortunately, because there are some higher priority things to do currently in libaco, so the Proposal "Addition of a build system generator to Test Suites" in Issue #5 would be postponed until all these goals are finished. Sorry about that.