[vala] (2 commits) Non-fast-forward update to branch wip/issue/713

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/issue/713' 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:

  d096a77... codegen: don't put symbols in internal header if they're in
  ac70491... vala: update use_header to reflect existence of header_file
  7407ee9... vala: remove use_header variable from CodeContext
  9349ac4... Rework API
  988d9ce... Use available "context"

Commits added to the branch:

  d6251a3... codegen: don't put symbols in internal header if they're in (*)
  7336e2a... vala: remove use_header variable from CodeContext (*)

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