ver 0.3

A couple of major changes and a few minor tweaks.

1. Periodic DWT code changed. The issue was Perfect Reconstruction wasn't working when filter length became larger than
 decmated signal. Code changed to implement actual periodic extension instead of using circular shift to mimic periodic 
extension. Change is strictly under the hood and header file remains unchanged.

2. Dyadic Zero padding is changed to padding the signal by the last value of the signal instead of zeros. 
