Compute response of filters
Fixed import warning
Incorporate feed back from simonster

All functions can take and ```Filter``` type.
Fixed indentation.
Use ```AbstractVector```.
Use list comprehension.
Don’t return frequency.
Run tests.
Change to freqz/freqs
Combine two hz functions using Union type
Removed return command
Merge pull request #32 from codles/master

Compute response of filters and test against matlab freqs and freqz
Documentation for filter response
Add link to filter response documentation
Clearer variable name

Use variable ``ejw`` as we are evaluating the transfer function at z=e^(jw)
Merge pull request #34 from codles/master

Added documentation and variable name change
consistent window types

all return 1d arrays except dpss, blackman and bartlett_hann faster, added window tests
Merge pull request #38 from gummif/master

Consistent window return types
Formatting fixes
Refactored periodogram/spectrogram

- Create a Frequencies type that doesn't need to allocate
- Make arraysplit an AbstractVector, allow simultaneous windowing and
  padding for FFT
- Periodograms and Spectrograms return objects
- Remove all unnecessary allocations
- Use FFTW plan interface as appropriate