Contrast/Gamma needs an icon

[Brother Gabriel-Marie]

Methinks that in the default iconset for the toolbar for Contrast/Gamma,
we need an icon for the button
and a fixup for the text

Here is mine in version .79

It says, "Conbright/Gammasat"

screenshot_xnviewmp_008.png

screenshot_xnviewmp_007.png

Also, there is the "Adjust Menu" - which also needs an icon.
In Classic, the tooltip for that button reads, "Adjust Brightness/Contrast/Gamma/Balance", but in MP it just reads, "Adjust".

I always use toolbar buttons, and am trying to make MP to be more like my Classic setup.