Unifying preprocessor macros

[addman2]

In TurboRVB we have macros that start with no under (RISC, PARALLEL, etc ...), with one underscore (_OFFLOAD, _CUBLAS, etc ...) and with two underscores (__SCALAPACK, __PORT, etc ...). Maybe it is time to unify all of them to one paradigm (like all of them will be only with one underscore.

We need to keep in mind this thing has to be changed also in the documentation.