Adds global setting for `gridUnit`

[peterramsing]

What kind of change is this? (Bug Fix, Feature...) Enhancement

What is the current behavior (You can also link to an issue) @lost gridUnit vw didn't do anything

What is the new behavior this introduces (if any) It does!

Does this introduce any breaking changes? Nope

Does the PR fulfill these requirements?

• [x] Tests for the changes have been added
• [ ] Docs have been added or updated

Other Comments

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (825b364) 100.00% compared to head (5366ffd) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #452   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           20        20           
  Lines          776       778    +2     
=========================================
+ Hits           776       778    +2     

Impacted Files	Coverage Δ
lib/lost-at-rule.js	100.00% <100.00%> (ø)

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[peterramsing]

...after playing with this more, I realized this breaks things if you use vw where you'd instead want vh. Globally setting this only works for one direction. 🤔