Awblib

What's Changed
* Fix Overflow Issue in CHS Modified (used in AAET) by JoeyTeng in https://github.com/JoeyTeng/AWB-Lib/pull/1

**Full Changelog**: https://github.com/JoeyTeng/AWB-Lib/compare/v0.0.2...v0.0.3

1. Added GW (Grey World), CHS (Colour Histogram Stretching) and AAET (Average Equalisation and Threshold)
2. Add a sample comparison among all methods.

**Full Changelog**: https://github.com/JoeyTeng/AWB-Lib/compare/v0.0.1...v0.0.2