- Fix bug #7300 (Prefs are never saved again after opening folder that
contains the user prefs JSON files in its subtree) - ensure that FileSystem
always knows we've read the JSON file before we try to write to it. We
don't want to enable the 'blind' flag since it will mean we virtually
always overwrite external changes to the prefs file, and we don't want to
start using file watchers to observe external changes on the fly since
we haven't yet deeply tested having multiple watch roots active at once.
- Rename confusing "filename" vars in PreferencesBase
- Fix JSLint errors in ProjectManager from #7026
Merge pull request #7376 from adobe/pflynn/fix-userprefs-writes

Fix bug #7300 (Prefs never saved again after opening ancestor folder of user prefs.json)