Fixing bugs and problems

[Onebeld]

This PR fixes the following bugs that were discovered while creating my own and as yet unannounced project:

• Fixed an issue where the color of buttons would flicker when hovering too much. This is more noticeable when hovering over buttons in the TitleBar.
• Fixed the PropertyGrid and removed the LabelColumnWidth property, as this property was not used anywhere.
• The window title and icon display have been fixed. If you haven't specified a DisplayIcon, it should be taken from the Icon property. A 10px height limit has been added for DisplayTitle, and the title text should now be displayed if not specified.

Changed:

• Updated to Avalonia 12.1.1.
• Improved logging to allow viewing task errors and Avalonia warnings, such as in Binding, for PleasantUI.Example.
• HotAvalonia has been removed as it failed to demonstrate effectiveness in developing PleasantUI.