Feature: delete commands from history and buffer

[Jaykul]

For the sake of building nice screenshots and scripts from buffer and history without the errors I make while trying to set it up, it would be awesome if I could select a command and delete it -- having it removed from the command history and also from the console output.

This way, when I'm trying to set up a repro and make a mistake on the 8th command, I could just delete that command and keep going, and still have a usable buffer and the ability to use Resolve-Alias on the history to build my script.

Ideally, this should be exposed as a cmdlet as well as in the UI.