Merge pull request #13 from benjello/master

working on widgets
per_capita_present_value and created new function to generate non-constant cohort.
aggregated present value is functionnal and tested but unsure about per_capita
per_capita_generation_present_value test and method are working. Nose reports no problem.
New method for Cohorts : filter to generate a restricted version of some cohort.
Unit test done and working.
the method extract_generation is screwed up and does not work yet, neither does the test.
Debugged the generation_extraction method. It can now handle non-zero ages arguments and border effects.

Now working as intended. The test also running correctly with nose.
Merge pull request #14 from jsantoul/master

utils.py & test_cohort.py Aggregated_present_value tested and OK
New method of Cohorts to generate age classes.

The test is good to go as well.
Cleanup of cohorte.py and utils.py

Expanded the documentation of cohorte.py
Merge pull request #16 from jsantoul/master

New method of Cohorts to generate age classes.
Tried to reproduce the work of C Bonnet.

Fail because of unknown bug with simulation.py file.
More details in Carole_Bonnet.py located in src\scripts.
Workaround to isolate the cohorte.py bug.

Nose functions correctly. Appears that the data make python to generate a string instead of a number.
Merge pull request #18 from jsantoul/master

Workaround to isolate the cohorte.py bug.