Link Manager 0.5.0 - Dropbox files can be set using a file chooser

I've added a file chooser that can be used to set the file path in Dropbox for the database. I've also moved the settings for the file choosers into their own preference nodes and added more settings stored for those file choosers. I've also fixed an issue where the program would allow a user to overwrite any file they save to with no warning that the file already exists.

What's Changed

• More settings stored for file chooser by @Mosblinker in #67
• 14 handle changing the external file location by @Mosblinker in #68

Full Changelog: 0.4.3...0.5.0