LUT update to include inferno and viridis

[N-Phillips]

Addition of two additional colour look up tables standard to python matplotlib. These are linear perception, greyscale and colour blind friendly.
Inferno inferno.csv

Viridis viridis.csv

Suggest that we change the default GeoPIXE LUT from STD GAMMA-II to inferno in the next major version update.

STD GAMMA-II

Inferno is close to STD GAMMA-II, i.e. black-purple-red-yellow-near white, while providing improved linear perception. Most users are unlikely to notice a significant difference.

[cgryan]

Good idea, will do. Linear perception is a good feature. Standard Gamma II is certainly not linear perception. But what it gives you is visible level changes, which view a bit like contours, making it easier to match a patch on an image to the concentration on a legend bar.

[cgryan]

Added these colour tables to "Display-->Colours" menu.
Cheers, Chris.

[N-Phillips]

Default to remain as STD GAMMA-II. Some users prefer a LUT that has distinguishable bands for ease of look up on a colour bar.

Functionality to add a different LUT default to config file will likely be added in the future.