Fixing failfast for single threaded benchmarking
Add test coverage analyse

Based on pytest_coverage.
Pythran currently has a pretty decent 90% coverage rate!
Fix a few compilation warnings
Make all tests use -Wall

The goal is to detect warnings in pythonic, *but*
this is not perfect as it also detects warnings in the generated code,
and test cases are full of warnings, although this commit fixes quite a
lot of them.

This only affects test cases based on TestEnv.
Harmonize integer template parameter types

Sometimes int was used, sometimes long, sometimes unsigned long.
Now size_t is used *everywhere*
Initialize ifilter internal structure properly

The filter operator was not copied but default constructed. It was not
an issue until someone used a bounded function. Bounded function hold an
internal state that *must* be propagated.

This fixes #76.
Constant value in a module may not be a scalar
Add some functions/constantes in string module
enable module constant as default value in a function
We can use ImportIds pass on a list
Fix context for functionanalysis
Fix assign and augassign management in ImportesIds
Correctly manage variable used before assignement in a If statement in a Loop
conversion from string have to be explicit to avoid conflict
Add constant evaluation time out in the TODO list
Add functions in string module

* strip, lstrip and rstrip
Handle second parameter in enumerate intrinsic

* second parameter is the first number returned (default is 0)
Add combinations in itertools

* combinations return all the possible combination of n elements in an iterable
example: [i for i in itertools.combination("ABC", 2)]
    -> [("A", "B"), ("A", "C"), ("B", "C")]

* it is a forward iterator as output order matter
Handle break and continue in Loop for FalsePolymorphism

* We handled break and continue as all other statements whereas
  they should create edges in the use-def graph