The nameing of the bootfiles have been historically inconsistent. To
fix that here is the convention to be used for all bootfiles after
2014-07.

1. The bootfile must reside in the directory whose name is the current
   CMUCL version for which this bootfile applies.  For example, as of
   this writing, the current version is 20e, so boot files must be in
   the 20e directory.
2. The name of the boot file shall be boot-yyyy-mm-n.lisp where
   yyyy-mm represents the year (yyyy) and month (mm) of the snapshot
   that is used to build from.  The boot files are numbered
   sequentially from 1 (n).  Thus, the boot-2014-06-1.lisp is intended
   to be built from the 2014-06 snapshot, and is the first boot file
   to be applied.
3. The boot file should describe what it is for.

If a cross-compile script is needed, we also have similar rules.

1. The script must be in the version directory, as for boot files.
2. The names of the script file must have to format
   boot-yyyy-mm-n-cross-aaa.lisp where yyyy, mm, and n have the same
   meaning as for boot files above.  

   A. The aaa field is flexible. 
      1. If it is not included, then the script is intended to be
         applicable to all architectures.  If aaa is given, then it is
         meant to be applied only for the architecture aaa.
      2. If the scrit is applicable to more than one architecture, the
         aaa field is dropped and the script must take care to include
         conditionals so that the script can be applied to all
         architectures.
   B. Additional information can be included if desired.

3. The script should describe what it is for.
