Added NAN control
Solved problem with quite_NaN binding
Updated matrix with new static versions of instance methods. Them return a new allocated matrix, allowing the  user to decide if use the in-place instance method or the new-matrix-allocation functions.
Added boot.percentil
Merge pull request #98 from pakozm/NAN

Added NaN initialization to matrix objects (in debug compilation)
Merge pull request #99 from pakozm/pako-devel

Added boot.percentil and new matrix functions
Merge branch 'master' into devel
Improved precentil computation
Added doc in statistics
Merge pull request #100 from pakozm/doc

Added doc in statistics
Added decay parameter in SGD optimizer
Merge pull request #101 from pakozm/devel

Devel