0.23.0: Merge with Numix upstream and rework Spotify theme

*  854d4df feat(oomoxify): rework color 'algorithm' to be closer to
original spotify colorscheme (and ship old version with more 'dynamic'
colorscheme)
*  2416dc9 chore(gtk320: button): increase default minimal size
*  ceb278a chore: merge with Numix upstream
*  5d35b74 chore(darker.sh): don't write debug messages
*  5d56661 feat(oomoxify): add '-w' option to 'normalize'
font Weight
*  7754eee fix(index.theme): put real theme name into index.theme - 3