[geary] (10 commits) ...Merge branch 'wip/90-304-image-dnd-paste' into 'mainline'

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  b4e3f19... First changes for supporting drag & dropped and pasted imag
  8ddd0b6... Merge remote-tracking branch 'origin/mainline' into wip/90-
  366b0ad... Cleanup inefficient GMime stream creation for attachment !3
  e765da3... Don't repeat the string search when replacing an inline ima
  e3cf826... Improve passing of inline dropped file through to vala !343
  e8bfe21... Tests for ComposedEmail.contains_inline_img_src and replace
  0f92956... Added a few tests for RFC822.Message - Inline attachments i
  21e0ecc... Tidy up, remove comment
  bc8e567... Mark ourselves busy while pasting inline images
  727f395... Merge branch 'wip/90-304-image-dnd-paste' into 'mainline'