New Greeter using only Gtk+

[tintou]

Fixes #2
Fixes #7
Fixes #13
Fixes #14
Fixes #31
Fixes #55
Fixes #69
Fixes #76
Fixes #108
Fixes #117
Fixes #159
Fixes #164
Fixes #175

Todo:

In Progress:

Done:

• No HiDPI detection. The greeter is running in LoDPI
• Brightness control in the power indicator is not working
• No indication when a user is logged in. Previously we overlayed a check mark on the avatar of logged in users Add check mark on logged in users #188
• Wallpapers aren't pulled in from each user. It's always showing the default UserCard: use wallpaper path fallback code from old greeter #189
• There is no feedback when a user fails to authenticate. Currently we shake the dialog and then make the password entry insensitive for that mandatory timeout period after a failed password attempt.
• Login as guest button does nothing
• Manual login button does nothing
• The fingerprint indicator should probably only show if the user has a fingerprint configured
• Wallpapers with a portrait aspect ratio don't show
• Entry should grab keyboard focus when appropriate (likely when typing occurs) Grab entry focus when typing #197 Greeter window sometimes doesn't grab focus [$60] #144

[danirabbit]

Just a few nitpicks as we go :)

[peteruithoven]

Great work on this!
Works perfectly on HiDPI.
I noticed two issues:

• The password field doesn't seem to grab focus.
  Unlike Greeter window sometimes doesn't grab focus [$60] #144, this happens consistently now.
  I noticed in the code that grab_focus is only called after the animate_error.
• There is something visually wrong with the buttons on the bottom. Compare:
  Buttons in Greeter:
  
  Buttons in Granite demo
  
  Looks like the text color is off and of the shadow color is the same as the text color?

[danirabbit]

🚀