ScalES-PPM

In the Fortran 90 part of the library, to always suit default kind INTEGER arguments, many generics only have specific implementations with default INTEGER arguments, because an i8 implementation wasn't needed so far. Unfortunately for bridging the gap to C several of these routines also assume default kind equals i4. Thus it would be preferable to have implementations for both i4 and i8 resulting in generics which work on any setting of default integer kind.