Clarify deprecation of undo: skip option

[jasonrudolph]

#282 updated the docs for TextBuffer::setTextInRange to deprecate the undo option. atom/atom#16956 points out that there are other public methods whose docs reference the undo option. This pull request updates the docs for those other methods so that they also identify the undo option as deprecated. It also emits a deprecation warning whenever the undo option is used.

[jasonrudolph]

To verify that the deprecation warning is wired up correctly, I ran Atom in dev mode and executed the following code in the console:

atom.workspace.getActiveTextEditor().getBuffer().setTextInRange([[0,0], [0,1]], 'foo', {undo: 'skip'})

Afterwards, Atom correctly reports the use of this deprecated option: