Probstatipy

Added
- `iqr()` can now take in a list of floats and return the interquartile range

Fixed
- fixed more import issues on spread.py I hope this is the last one.

Fixed
- fixed more import issues on spread.py

Fixed
- spread.py was importing from `pystats_central`. This module doesn't exist as it was renamed to `statspro_central` then `central`.

Initial Release
A package for statistical analysis containing the following modules:
- central.py - Computes measures of Central Tendancy such as:
- mean
- median
- mode

- spread.py - Computes measures of dispersion/spread such as:
- variance
- standard deviation
- mean absolute deviation
- range
- interquartile range