0.92a:
 - fix a bug named Scope.clear.
 - fix a bug on module Unix.
 - fix a bug on operator **.

0.92:
 - based on Objective Caml 3.04.
 - 'nmlo' (native-code compiler) is implemented.
 - 'ntopgen' (toplevel system generator) is implemented.
 - 'nmlmake' is changed to 'nmakegen'. 
 - bugs fixed.

0.91:
 - based on Objective Caml 3.01.
 - the usage of record follows the nML definition.
 - nML type information is displayed.
 - bugs fixed.

0.9a:
 - fix the case of "fun f x = 1 | g x = 1"
 - fix twisted error messages for an application
 - fix bugs on inferring types of modules
 - fix the case of "if true then 1"

0.9:	
 - an nML type-checker is embedded.

before:
 - an nML compiler was built on Objective Caml compiler (2.04-3.00):
   nML parser + nML-to-OCaml translator + OCaml compiler
