Hex view color scale could be more informative

[mkow]

Currently hex view colors looks nice, but IMO they are not too useful. We can improve this by varying color intensity (instead of hue) according to byte value, this way it's much easier to spot patterns in the data. For an example of this coloring scheme see Hexplorer.

Also, another idea: (could be customizable in options) Colorize hexes in various "buckets": e.g. a-zA-Z range in one color, 0-9 in another, 0x00-0x20 in another etc.