[Ecls-list] Latest changes

[Juan Jose Garcia Ripoll]

* Introduced --with-system-{boehm,gmp}. --enable-local-{boehm,gmp} still
  work but are deprecated.

* Fixed the configuration flags for the different modules. Now, if the
  user does not select them, they are not built/installed (There were
  some problems with obsolete shell statements like
     test ${option}
  instead of
     test ${option} = yes

* Backquote, comma, comma-at, and comma dot (` , ,@ ,.) are now implemented
  using a common macro EXT:UNQUOTE. By default, the reader produces forms
  using this macro, which print as they were read
    (format nil '`(foo , at a)) => "`(foo , at a)"
  and it is at evaluation time that they are expanded into calls to LIST,
  LIST*, APPEND and NCONC.

* The previous implementation seems to solve a problem with the interaction
  between #n# and backquote. For instance, the following form
    `(foo #1=(faa ,a) #1#)
  now produces the right expansion.

* In pathnames, all strings are converted to simple strings without
  fill pointers because otherwise routines like probe-file, chdir, etc
  which deal with the C world, become too complicated.

Hopefully after these fixes I will be able to continue working on a port 
of Slime ;-)

Juanjo