Merge pull request #3 from abate/master

Add an ocamlbuild based makefile.
Updated some stuff to fit the new Makefile which uses ocamlbuild:
1. Replaced the use of "zephyrus" executable to "zephyrus.native" in all test scripts.
2. Updated the .gitignore file.
Advanced the intermediary internal types.
Advanced even more in intermediary types.
Moved the SetOfList, MapOfAssocList, MapOfList modules to the Helpers module.
Finished adding translation exceptions to the intermediate types translation.
Transformed the package dependencies and conflicts to a new form too.
Half-done specification translation into intermediary types.
added generic sets and maps with useful functions
Merge branch 'master' of https://github.com/aeolus-project/zephyrus
testing some possible structure for the code
Finished specification translate into intermediary types.
Created a new subfolder "constraint_generation". Renamed the module Constraints to Constraints_generation. Amended the _tags file accordingly.
Added "solvers" and "constraints" subfolders.
Cleaned up few files useless now (i.e. after introducing ocamlbuild).
Renamed the current work files "at*" to a little more meaningful names. In fact they should be developed on a separate branch...
Added the SetOfMapValues module to Helpers.
In the middle of writing the new Typing_context module.
Still in the middle of writing the new Typing_context module.
Finished the new Typing_context module.