Improve carryover and carryover drawers

[casch-at]

Either copy or delete.

~~#274~~ , ~~#267~~, ~~#264~~, #248, #190

[chasecaleb]

For what it's worth, I'm really interested in #190 (carrying over an entire "project" until completed). If it helps any/to get discussion giong, it seems like there's two ways of handling it:

1. For any todo items that carry over, find the closest ancestor heading that does not have a TODO property. Carry over it and all of its children, minus those that are in a completed TODO state.
2. The same as above, except carry over the top-level heading instead of the closest ancestor.

To given an example, given an initial org file like this:

* My project
** Foo
*** DONE Do the thing
*** TODO Something else
*** Miscellaneous note
** Bar

Method one result:

* My project
** Foo
*** TODO Something else
*** Miscellaneous note

Method two result:

* My project
** Foo
*** TODO Something else
*** Miscellaneous note
** Bar

The difference between the two in this case is whether or not "Bar" would carry over. I keep going back and forth about which one is more useful and can't decide. I don't think it makes a huge difference to me personally, but I can imagine other people having strong preferences for either since it depends on how you structure your notes. Maybe implementing both with a variable to customize would be worth it, I'm not sure.