[misc] add Connector - a utility that automates disconnecting signal handlers
[connector] Make safe for repeated disconnections.
[alt-tab] Show windows from all workspaces. Highlight "urgent" windows.
[Alt-Tab] No gradual fade-in of preview backdrop.
[Alt-Tab] Respond to Home and End keys. Remove obsolete key bindings.
[Alt-Tab] Avoid duplicates of windows displayed on all workspaces.
[Alt-Tab] Scroll icon list earlier when we are approaching the edge.

Before, we only scrolled when we reached the egde, now  we
scroll when when we are about four items from either egde.
The new behavior should only be visible when we have a lot of
windows open and the icon list cannot show all windows without
scrolling.
[Alt-Tab] When activated on an empty workspace, don't default-select any window at all.
[Alt-Tab] Enable multi-line title labels.
[Alt-Tab] Avoid different icon heights when scrolling through the icons.

Since the selected icon may have a different style than the rest, it's
bad to have that icon be the model for all icons.
[Alt-Tab] Size allocation is smoother if 'squareItems' is false.
[Alt-Tab] Add PageUp- and PageDown- sensitivity.
[Alt-Tab] Size the icons according to the number of windows on the current workspace.
[Alt-Tab] Space key makes switcher (icon bar) stay on screen without the need to hold down the Alt key.
[windowManager.js] Don't destroy Alt-Tab popup from the outside.
[Alt-tab] No quick fade-out of old window preview, just destroy the clones.
[Alt-tab] Handle window-removed event.
[Alt-Tab] Ctrl+w in persistent mode (Ctrl+space) closes currently selected window.
[Alt-tab] Refactoring: use accessors to reduce the number of duplicated variables.
[Alt-tab] Refactoring: minor cruft removal.