Core: Icons: Icon protocol is now async, svg icons can have any <svg> attribute forced

(integrated from trunk branch change c5f8f71 by Nathan Rijksen <n.rijksen@gmail.com>)
Core: Icons: Support diffent types of icon namespaces

(integrated from trunk branch change 87a3dee by Nathan Rijksen <n.rijksen@gmail.com>)
Schemes: Updated base16 color schemes to latest version

(integrated from trunk branch change 4ee443c by Nathan Rijksen <n.rijksen@gmail.com>)