core: use generic PKG_MEM_ERROR, SHM_ERROR and _CRITICAL helper defines in core

core: use generic PKG_MEM_ERROR, SHM_ERROR and _CRITICAL helper defines in core

    - refactoring of the core to use generic PKG_MEM_ERROR, SHM_ERROR,
      PKG_MEM_CRITICAL, SHM_MEM_CRITICAL and SYS_MEM_ERROR helper defines
    - unify many different error messages in different spellings
    - add a few missing error handler for allocation errors after (found
      with a complete review of all memory allocation functions in core)
    - no other functional changes, change has been reviewed two times