_tooltip.scss: replaced hard-coded 85% with `$tooltip-max-width`

tooltip show become too wide on large screens, since their `max-width:
85%` refers to the whole width of the screen. I have added a parameter
`$tooltip-max-width` and chose a default of `300px`.
reverting some code in topbar.js - mobile_show_parent_link didnt seem to ever have functionality
Remove check for the background color of blue inside _panel.css during a loop's chech on whether or not it should change the text color of panels
Fix the centered column floating glitch by targeting specific selector, instead of using !important.

Should fix both #4200 and #4624.
Moving CSS rules that are irrelevant to $size out of the mixin grid-html-classes($size).
Adding size-specific centered & uncentered styles into @grid-html-classes mixin.
Avoid introducing new variables
Merge pull request #5186 from MrOrz/master

Remove `!important` and reorder certain styles in grid system to fix centered grid
Merge pull request #5190 from karland/patch-2

_tooltip.scss: replaced hard-coded 85% with $tooltip-max-width
Modify _panel.scss to address pull request [#5187](https://github.com/zurb/foundation/commit/e806a94572f7aa220db0ed361d606799f796d4f4)
Merge branch 'master' of github.com:zurb/foundation into 5.3-wip
renamed toolbar to iconbar
Merge branch '5.3-wip' of github.com:zurb/foundation into 5.3-wip