Change numeric values to float (python2)

Python2 doesn't support automatic conversion from int to float in a
division.
Remove debug line
Resultion of floats prooblems for MDCT

Resolve conflict between python2 & python3 in MDCT
Create new class MatchingPursuit

This class implements the Matching Pursuit algorithm
Arguments :
  - dictionary -> an mdct dictionary used created by Mdct
  - m -> the number of atoms given by the decomposition