Basically, everything that does not depend on a BufferView should move
there. Some methods that do not seem to need a BufferView, like
selHandle or IdxFirst or push actually depend on it and could not be
moved.
This allows to simplify a few uses of recordUndo helpers.
- Move some methods to DocIterator: nextMath, prevMath, getPossibleLabel,
getEncoding;
- Move some methods to CursorData: setCursor, setCursorSelectionTo,
(setCursorTo|normal|reset)Anchor, (set|clear)Selection,
sel(|ection)(Begin|End), selectionAsString, info, currentState,
(mark|clear|check)NewWordPosition, fixIfBroken, sanitize, all undo
related methods, reset, isInside, leaveInset, current mode;