Added Setoid definition.
Added src/math/setoid.v to targets.
Merge branch 'math' into integration
Renaming the math stuf to follow the capitalized module convention.
Added a PartialOrder definition.
Merge branch 'math' into integration
Added a default .gitignore file.

It ignores the Makefile for it is automatically generated and emacs backup
files (finishing by '~').
Merge branch 'build' into integration
Merge branch 'integration' into math
Added TotalOrder class with related instances.
Merge branch 'math' into integration
Merge branch 'integration' into integer
Renamed the mltypes directory according to the usual Coq naming
conventions.
Reword some doc.
Added base arithmetic operations and rewrote the coercion from Z with them.
Renamed operations to define ordering instances.
Merge branch 'integer' into integration
Ignore intermediate files or object files.
Merge branch 'build' into integration
Merge branch 'integration' into math