SwineWM 0.3.0

Mouse and decorations (see the roadmap in
doc/project_summary.md): focus follows mouse,
moving and resizing windows with the mouse, window borders and title bars
in the client.* colours, tabbed and stacked title bars, plus a
replacement for the "Open with" dialog in swinemenu.

Added

• Mouse support, ported from sway: focus_follows_mouse yes|no|always,
  floating_modifier <mod> [normal|inverse] ($mod + left button moves a
  floating window or drags a tiled one to another place, $mod + right
  button resizes either), tiling_drag, tiling_drag_threshold,
  mouse_warping output|container|none, and mouse bindings
  (bindsym --whole-window $mod+button4 workspace prev).
• Window decorations, as in sway: border none|normal|pixel|toggle,
  default_border, default_floating_border, client.focused,
  client.focused_inactive, client.unfocused, client.urgent,
  smart_borders, hide_edge_borders smart|smart_no_gaps and
  opacity. On Windows 11 the border is the window's own (1 px) border in
  the child_border colour; border normal keeps the window's title bar
  and colours it, pixel and none remove it. Tiled windows get square
  corners. Everything is undone when swinewm exits, after a crash and by
  swinewm --recover. sway's defaults apply, so title bars now follow the
  client.* colours (dark blue for the focused window) unless the config
  sets other colours.
• Tabbed and stacked containers get title bars, as in sway: one row of
  tabs, or one row per child, in the client.* colours with font,
  title_align, titlebar_padding, titlebar_border_thickness and
  client.focused_tab_title. A click on a tab focuses it, the wheel
  switches tabs, and title bar mouse bindings (bindsym button2 kill) work
  on them. title_format sets the tab titles.
• The drop zone of a dragged tiled window uses client.focused's
  indicator colour.
• windows_theme dark|light|auto (swinewm extension, off by default):
  switches Windows' light/dark mode, which Windows' dialogs and most
  applications follow, while swinewm runs; auto follows the brightness
  of the bar's background. Your own setting comes back on exit, after a
  crash and with swinewm --recover.
• swinemenu --open-with <file>, a replacement for Windows' "Open with"
  dialog (which stays empty without Explorer): it lists the programs
  registered for the file's type and opens the file with the chosen one.
  swinemenu --install-open-with adds "Open with swinemenu" to every
  file's context menu and uses swinemenu for files no program is set for;
  --uninstall-open-with removes both.

Fixed

• A floating window dragged by its title bar onto another monitor now
  joins the workspace shown there, as in sway.