Pretty much finished hacking configure. Any requests?

I have pretty much finished hacking the configure scripts.  Please let 
me know if I have broken anything.

While my configure-fu is strong, I will happily consider suggestions for 
other changes.

The main purpose of the changes was to untangle the windows build
  - built process agnostic to choice of lisp
  - build the CHM docs in the doc/info subdirectory at build time
    (Not in the install directory during "make iss"
  - when preparing to build a windows installer, install wxmaxima and 
gnuplot
    from to top top level (not interfaces/xmaxima/win32)

It is now much easier to make an windows installer using a lisp other 
than gcl.

I also added configure options
   --enable-openmcl-exec
   --enable-ccl-exec
   --enable-sbcl-exec
   --enable-clisp-exec
to make executables using ccl, sbcl and clisp.