Fixes an infinite loop in the layoutModel atom synchronization that
would cause the atom to update indefinitely when the root node is
deleted.
Also adds a dedicated `disabled` flag for the IconButton decl so we can
disable the onClick handler when the button is disabled.
Also updates the Magnify toggle button to use this new flag, so that
when there's only one leaf in a layout, the magnify button is disabed.
This PR adds back WebGL acceleration (enabled by default) for XTerm. It
also adds back link handling and adds a new option (disabled by default)
to open all links internally as a new web block.
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Co-authored-by: sawka <mike.sawka@gmail.com>
