Consistency in y/n prompts

[carlynorama]

Some accept just y or just Y some both. (swifty-install.sh, the intro to the package accepts both.)

MacOS.swift and Linux.swift go their own ways in asking for confirmation (line 121, 135 respectively) in their use() functions for overwriting symlinks, only accepting y, but not warning on a Y.

perhaps these functions should be using

promptForConfirmation(defaultBehavior: Bool) from Utils.swift (line 19)?

[patrickfreed]

Yeah we should definitely be consistent with this. Merging swiftly-install.sh into swiftly itself will help with that too, we just need to make sure to use the same promptForConfirmation everywhere once we do that.

[adam-fowler]

@cmcgee1024 Can you verify your swiftly init PR is consistent