Merge branch 'develop' of https://github.com/Drayshak/MultiMC5 into feature_yggdrasil
Merge branch 'develop' of github.com:MultiMC/MultiMC5 into feature_yggdrasil
Add icon for when no default account is selected

Also fixed a bug where the icon on the accounts button wouldn't change
when the user checked the "Use as default" checkbox in the account
selection dialog.
Tweak the layout of the accounts button
Verify access tokens before launching Minecraft

Kind of an important thing to do... Heh...
Rework the password dialog

It's now used as a general purpose "account edit dialog". It'll be used
for entering usernames, passwords, or both.
Nuke dead code