refactor the gathering of compile time settings after discussion with @sjplimp

- remove feature to record the compilation time and date
- remove 'echo -n' based "progress bar"
- update output format for "lmp_machine -h" to be consistent with help output
- move generation of lmpinstalledpkgs.h to be a separate target depending on
  all sources and headers in src folder. this way it is only regenerated
  when files are modified or packages installed