Don't save per-account settings if login not fully successful

The viewer resets your "per-account" settings when you try to log in too fast after a crash ("the region is logging you out") and then quit the viewer before a successful login.

See comment and link to fix in https://jira.secondlife.com/browse/STORM-1794?focusedCommentId=305543&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-305543

Repo:
Somehow crash your viewer

Try to log back in immediately: You get a message "The region is logging you out"

Quit the viewer at this point: your per-account settings are now zorched, as they were not yet read in, but are being written out.