Command: Implement Create Rebracer Settings File

Also reorganize constants
Fix misc issues

Avoid double-loading settings on solution switch
Fix change detection
Only read Property.Value once

Boosts save performance
Command: Tweak display name

Clarify that this does not copy an existing settings file
Warn when users add a settings file elsewhere
Workaround for NDA bug

Also fix typo
Warn when removing settings file from solution
Notifications: Copy WpfGrowlNotifications source

Includes minor spelling & code analysis fixes
Refactored Notifications class to use [CallerMemberName]

Thanks to @IvanLeonenko
Notifications: Implement INotificationService
Notifications: Fix Code Analysis issues

Fix namespace casing
Use Notification objects directly in Tag
Use Uri instead of string
Notifications: Use VS theme colors
Notifications: Remove unused Id property

Use DataContext instead of Tag.
Also privatize implementation property
Notifications: Fix XAML property indent
Notifications: Fix close button layout

Fixes position & borders, and contrast
in Light theme.
Notifications: Fix animation & layout