#1488 Improved Readonly Operation

[David Mittnacht]

Sometimes I want a master KeePass database, but to be able to issue readonly copies that people might cart around on USB sticks, etc. Any (or all) of the following would facilitate this operation:

1. Set a configurable home location for a database (drive and path or UNC). If the file was opened from another location, it was implicitly read-only.
2. Set some indication in the UI to indicate readonly mode.
3. Detect a readonly setting on the file attributes when opening. Note, this is closely related to the next suggestion.
4. When closing a readonly database, allow a "discard changes" close - otherwise, you can't close the program at all without Task Manager or a Save As.