Publish should clean the output folder

[billwert]

If you publish into a folder that has binaries in it, the existing binaries aren't removed. For example, if you had a build system publishing to a specified folder with --output, were publishing stand alone, and switch to shared framework, your output folder will still have all the stand alone binaries in it.

[blackdwarf]

@billwert hm, looks like a switch to me, something like --remove-existing or similar. Similar to the way publish in VS works, you have that little checkbox.

[TheRealPiotrP]

Moved to SDK repo