Cpluspalette 1.1.0

What's Changed

• K mean w/cielab by @trollLemon in #28
• Median cut option by @trollLemon in #29
• unordered_set for color filtering by @trollLemon in #30
• Update readme by @trollLemon in #31

Full Changelog: v1.0.3...v1.1.0

Re-implemented K mean clustering based off this paper: http://www.ijimt.org/papers/102-M480.pdf.
Performance of the data clustering was improved

Unordered_sets are also used by the software to filter out color duplicates; this improved the palette quality for images where the color balance is terrible: for example, the software provides a good palette for the following image gotten from https://wallpaperaccess.com/abstract-minimalist:

by this method.