* feat: alert user via nagview if file cannot be saved
it will prompt the user to choose whether they
want to save to another location and perform
the save as command
* refactor: change defer draw call to thread
* feat: log error when attempting to save doc
* Add `Doc:get_selection_idx`
* Make multicursor paste add a cursor at the end of each paste
* Better manage paste of multicursor whole line copy
* Document `Doc:get_selection_idx`
* Keep track of last added selection in `Doc`
* Make use of `doc.last_selection` in `Doc` commands
* Make `Doc:get_selection` return the `Doc.last_selection` if possible
When a command is performed with parameters, those are now passed to the
predicate.
The predicate can then return, after the validity boolean, any other
value that will then be passed to the actual command.
If the predicate only returns the validity boolean, the original
parameters are passed through to the actual command.
This allows predicates to manipulate the received parameters, and allows
them to pass the result of an expensive computation to the actual
command, which won't have to recalculate it.
String and table predicates will now also return `core.active_view`.
* Modified autoreload to use new dirwatch infrastructure, and added in nagview to verify that fs changes don't stomp on our changes, unless you want them to.
* Split out reload functionality to actual document, and added in a thread to check the document, in the cases where it wouldn't be covered by dirwatch.
* As per request from jgmdev, added in ability to show nagview always.
* Changed things over to use dirwatch.
* Made sure we redrew things, added in a contingency in 'save' for times when we load a non-existent file, and added some checks.
When using `doc:move-to-{previous,next}-char` in a selection, we were
moving the cursor to the character before the initial/after the last
character of the selection.
Now we follow what other editors do and move it to just before the
initial/just after the final character.
This is needed for example when a selection has both `line1` and `col1`
at 1, and the left arrow is pressed: `line2` and `col2` change, while
`line1` and `col1` don't, but we still want to scroll.
