[vala] (8 commits) Non-fast-forward update to branch wip/issue548

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/issue548' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  182bc0c... vala: Don't just guess and check for a matching base_interf
  1023f90... vala: Search in all interfaces for an implementation match 
  52aa5b4... codegen: Do a proper check before connecting inherited impl
  2f8e9d3... WIP vala: Allow Method.compatible() to be used for expected
  c4729b0... WIP vala: Allow explicit interface methods to be virtual

Commits added to the branch:

  af25bc3... vala: Use clearer error message for automatic properties in (*)
  7432288... girparser: Skip "source-position" elements (*)
  826e6c0... vala: Don't just guess and check for a matching base_interf
  f201859... vala: Search in all interfaces for an implementation match 
  df800b1... codegen: Do a proper check before connecting inherited impl
  149ca48... WIP Remember implicit implementations
  7310de3... vala: Allow explicit interface methods to be virtual
  f5542a7... WIP vala: Allow Method.compatible() to be used for expected

(*) This commit already existed in another branch; no separate mail sent