- use static/const
- return instead of ptr-parameter, &ref if more than one return
- replace macros from header with inline functions
- remove useless/old comments
- fm_exp moved to math_special (exp2 was already there)
- use std::min/max template instead of macros
- use memory->create for dynamic arrays (still 1-indexed with macro)
- remove _ from function names, adjust method visibility
- move MEAM class into LAMMPS_NS namespace
- move inclusion of meam.h header to pair_meamc.cpp to reduce namespace pollution
- use forward declaration for MEAM class reference
- make that class reference a pointer and add a destructor
- replace MAX/MIN macros with versions compatible with older compilers
