Revert changes to the searchfield appearance

Some stashed code code got mixed into a previous commit that messed up
vertical alignment of the searchfield. Reverted here.
Remove fixed position sidebar < 1280px wide screen

On mobile and small screens, the global nav and the nav bar should
both be regular relatively-positioned horizontal bars, and the
sidebar_col element should be floated left, not fixed.
Testing - new color scheme
No alternate sky
No lighter sky
Changed more color name references
There is no river
new logo images
Add "samltest" icon to providers

Corresponds to v2.2.10 of current Quilt, ticket UX-54 in Jira.
Set max-height on sidebar col

Without a sensible max-height in all the breakpoints, the sidebar column
was overflowing the visible area and it wasn't possible to select the
last menu items when the menu was expanded all the way.
Set default link color to teal
Experimental: introduce provider-hex classes

for hexagons w/provider-specific background color.
Whitespace cleanup