Make "take" preserve semantics of the target that is selected

[pokey]

Instead of having a "from" that sets a special implicit target (see #2155), we would like to use "take". The problem is that you lose the rich semantics of the target. Eg "take arg chuck this" won't clean up the comma

The solution

• the "take" action will also set a special target at the same position that it sets the cursor
• we highlight the target, so that the cursor highlight color will change
• next time they issue a command that uses "this" or implicit mark, it will use the stored target instead of just raw selection
• if selection changes before selection is used, we drop the target
• as extra credit, we keep a list of past targets so that if they "curse undo", we can restore the old stored target

See #2155 (comment)