Restore height override before height calculations.
Build: Switch advpng for grunt-contrib-imagemin

- Restricted to sprites at this time
- No settings tweaking have been done
Merge pull request #3791 from nschonni/v4-replace-advpng-with-grunt-contrib-image-min

Build: Switch advpng for grunt-contrib-imagemin
Changed 'overlays' to 'overlay' as discussed in PR #3683.
Updated front matter for overlay demo pages to use singular of 'overlays'.
Merge pull request #3793 from thomasgohard/overlays-to-singular

[Overlay] Change plugin name to singular
Overlays: Fix missing rename

Minor whitespacing fixes by EditorConfig
Merge pull request #3797 from nschonni/v4-fixed-overlay-rename

Overlays: Fix missing rename
Merge pull request #3789 from thomasgohard/fix-equalheight-window-resize

[Equal height] Restore height override before height calculations
Build: Move image compression to dist only
Merge pull request #3798 from nschonni/v4-imagemin-all-dist-images

Build: Move image compression to dist only