Update color-schemer (incl. new blend-modes system object).
Update gradient mixins; more flexible linear gradient and add new rainbow or stripes gradient mixin! Plus add some gradient color variables.
Different comment style for grid set system partial.
Tabs instead of spaces.
Update font icons object partial syntax and add new Fontello icons (with Fontello's config.json for adding new icons easily); remove unused Entypo font icons.
Update analytics logic; plus add Google Universal Analytics, GoSquared and Segment.io tracking options.
Update modular-scale system partial.
Fix mobile/tablet detect logic for image sizes.
Update to latest Mobile_Detect plugin script.
Future proof.

When using a colon to define your if/elseif conditions, you must not separate else if into two words, or PHP will fail with a parse error.
Disable debug mode by default and remove from variables partial.
Output comments in generated and minified script files.
Update grunticon folder naming, import logic and structure.
Update Mixture config; add "simpleModeFileTypes" to set the file types that will cause a reload/refresh in simple mode.
Mixed tabs and spaces.