Replaced the process icon with a pin icon (for top-most).
The color-palette button is hidden (collapsed) until further implementation.
The pin button is now represented by a checkbox, using the click image when it is checked.
Visibility is set for all elements in the top bar - not only buttons.
The pin checkbox sets a notes topmost value.
Changes in Topmost is saved in the xml file.
Notes cannot be closed except when shutting down Windows or deleting notes.
Updated all icons to a new and simpler style.
To match with the new icon style, the icons are placed without spacing between each other.
Added an additional icon for pin, used when it is 'active'.
The pin is not hidden if it is checked.
Replaced the map pin with a more 'pin'-like image.