Refactor Makefile

[paulapatience]

Hi Sebastien,

Generally Makefiles are in the root of the project, which allows you to type make without further changing directories. In addition, some of the Makefile's variables, such as COMPILATOR, COMPILATOR_OPTIONS, etc., differ from the standard names. This is inconveniencing for users accustomed to CXX, CXXFLAGS, etc., when overriding the flags on the command line. Finally, I see that the dependencies are manually specified in the Makefile. There is a way to automatically generate them with gcc's -M* flags.

If you give me the go-ahead, I can prepare a PR addressing these issues.

[sebastienledigabel]

Ok as long as it stays simple. Thanks Paul.