* Start transform tests & slight optimization in RandomTimeShift

* Add new length check for TimeCrop tests

* Code style

* excess bandwidth is defined in porportion to signal bandwidth, not sampling rate, thus needs to be scaled by the samples per symbol

* filling in a comment to describe modification to code

* excess bandwidth is defined in porportion to signal bandwidth, not sampling rate, thus needs to be scaled by the samples per symbol

* filling in a comment to describe modification to code

* * cutoff frequency for LPF now randomized when using 'rand_lpf'
* derives a transition bandwidth from the cutoff frequency
* uses filter length approximating function for the randomized LPF

* using filter estimation function for pre-computed LPF taps

…104)

* Initial benchmarking code.

* Some benchmarks

* Adding initial benchmarks.

* Fix action.

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* Tests for visual inspection of modulation generation. (#102)

* Optimizations show significant improvement in generation speed.

* Nominal behavior after using scipy.