Added negative slicing for single integer indexes + tests
Change filter order specification to filter taps number specification.
filter test written and passing
Merge pull request #153 from ktakagaki/end_slicing

End slicing
Merge branch 'master' of https://github.com/scalanlp/breeze into filter1
filterLP, filterHP, slight refactoring in parameter order
fourierShift/fourierFreq first shot
fourierShift moved out to extends UFunc, tests passing