v2.6.0 - Area selection, chat files, grouped navbar actions

Minor release. Nothing to change in your code. Coming from 2.5.2? Read the 2.5.3 notes first: MStack spacing became the gap between children and the styles moved into a cascade layer.

• MWeekGrid: selectable lets people drag over the grid (mouse, pen or finger) instead of clicking every hour. Live preview, onSelectRange / onSelectingRange, whole day / hour from the headers, Shift + arrows and Enter from the keyboard.
• MChat (Pro): messages take attachments (download chips). MChatInput takes any file type via attachAccept, limits with maxFiles / maxSize, works as a controlled field, inserts text with ref.insertText() and shows your own actions.
• MNavbar: with collapseActions the action groups and the burger stay together at the end of the bar on desktop.
• Focus outlines on about 30 components use the theme focus colour, visible in both themes.
• MScheduler (Pro): the keyboard move frame shows the time in narrow week columns.