[gnome-software] (12 commits) ...Merge branch '1148-key-colour-generation' into 'master'

[Phaedrus Leeds <mwleeds src gnome org>]

Summary of changes:

  9c4abdd... gs-app: Fix a typo and add annotations to a gtk-doc comment
  d095675... gs-app: Support override key-color values in appstream data
  f352fbd... lib: Split key colour generation out into a separate file
  e31bab2... tools: Add a profiling tool for key color generation
  2918955... lib: Rework key color extraction code
  9809dd7... lib: Use GArray for key colors rather than GPtrArray
  3f090cd... gs-feature-tile: Choose the best key colour as the backgrou
  72af751... gs-feature-tile: Recalculate background colour when style c
  a684301... gs-key-colors: Use nearest rather than bilinear scaling for
  b370a1a... Fix copyright headers for EOSF
  cea6300... build: Bump plugin API version for recent GsApp API changes
  16065db... Merge branch '1148-key-colour-generation' into 'master'