Collapse purple theme colors

[fbarl]

UI components part of #259.

After some tiny normalizations, the primary colors spectrum consists of the following colors (rough usage estimates in brackets):

hsl(240, 20%, 25%) - charcoal (20)
hsl(240, 20%, 30%) - gunpowder (22)
hsl(240, 20%, 35%) - mulledWine (4)
hsl(240, 20%, 42%) - cometDark (1)
hsl(240, 20%, 45%) - comet (3)
hsl(240, 20%, 49%) - kimberlyDark (4)
hsl(240, 20%, 57%) - kimberly (7)
hsl(240, 20%, 59%) - lavender (44)
hsl(240, 20%, 65%) - amethystSmoke (14)
hsl(240, 20%, 75%) - logan (6)
hsl(240, 20%, 79%) - blueHaze (5)
hsl(240, 20%, 90%) - mischka (9)
hsl(240, 20%, 91%) - athens (10)
hsl(240, 20%, 95%) - athensGray (6)
hsl(240, 20%, 98%) - whiteSmoke (14)

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New color system (dropped 4 colors from above):

hsl(240, 20%, 25%) - purple900
hsl(240, 20%, 30%) - purple800
hsl(240, 20%, 35%) - purple700
hsl(240, 20%, 45%) - purple600
hsl(240, 20%, 50%) - purple500
hsl(240, 20%, 60%) - purple400
hsl(240, 20%, 65%) - purple300
hsl(240, 20%, 75%) - purple200
hsl(240, 20%, 90%) - purple100
hsl(240, 20%, 95%) - purple50
hsl(240, 20%, 98%) - purple25

The naming convention was inspired by Material Design and the discussion in #218.

cc @bia @miklosp

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Note: I also added the default tooltip info on the colors preview page and relaxed the saturation sorting criterion a bit.

[foot]

Nice one! LGTM

[miklosp]

LGTM!