Bug fixes and performance improvements

Just joking. mbpfan v2.0.1 contains minor improvements to the codebase and the makefile. In particular:

• Makefile now supports correctly the -j flag (you happy now, Gentoo users?). Credits @gktrk
• Use of macros is now protected thanks to lots of round brackets. Credits @Ndolam
• The function for checking mbpfan requirements made use of unnecessary system calls to execute code. Deleted them while keeping functionality. Credits @Ndolam