Modified the policy about global objects inside the kernel. The previous

  policy was to forbid them, by checking with a script that there were none.
  This policy was found to be too restrictive, so a new script
  (miosix/_tools/kernel_global_objects.pl) moves the pointers to function that
  cause their construction in a separate section compared to the one used for
  the application global objects. Thus the global objects are now divided in
  two group: the kernel ones, which are called before boot, and the application
  ones, which are called after boot, right before main. This is made necessary
  by the fact that Miosix allows an application to be statically linked with the
  kernel, so both end up in the same binary file.