* Run screenshotter using Chrome 83 and Firefox 76
* Update screenshots
* Update NegativeSpace-chrome screenshot
The new screenshot is correct as per #1194.
* Update Units-chrome screenshot
The new screenshot is correct as per #732 and compared to Firefox.
* Update screenshots
* Implements the alignat environment for flexible math spacing
* Renames alignat[*] to alignedat and factors out duplicate code of aligned and alignedat as alignedHandler
* Adds aligned at to screenshotter
* alignedat screenshots
* Implements the alignat environment for flexible math spacing
* Renames alignat[*] to alignedat and factors out duplicate code of aligned and alignedat as alignedHandler
* Adds aligned at to screenshotter
* alignedat screenshots
* fix style nit
* fix lint
