Undo/redo or any manual change to document while in subcomponent edit mode can cause various parsing errors

Undo/redo is indistinguishable from manual text change in ComponentTextModifier. Neither properly updates ComponentTextModifier offsets when document is in subcomponent edit mode, usually leading to various parsing errors.

When an unexpected non-whitespace change to document text is detected, ComponentTextModifier should be recreated from scratch. It's bit problematic as this requires a rewriter view attached to original document model, but rewriter view is currently attached to the in-file subcomponent model.