toggle-preview-wrap (and -wrap-word) modifies t.activePreviewOpts.wrap,
but change-preview-window resets t.previewOpts to t.initialPreviewOpts,
discarding the user's toggle. Carry wrap and wrapWord over so toggles
survive a layout change. Explicit wrap / nowrap tokens in the new spec
still win, so cycling and the empty-token reset are unaffected.
Close#4791