Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

mri1.test
; RUN: echo create %t.a > %t.mri
; RUN: echo save >> %t.mri
; RUN: echo end >> %t.mri

; RUN: llvm-ar -M  < %t.mri
; RUN: llvm-ar t %t.a