Fork MiniPCR version of 'Prepare Amplicon Library'

A version of 'Prepare Amplicon Libraries' to support MiniPCR should be created separate from the current version supporting 16S, using the current version as a template. Since the default values are likely to be different, it appears we will need two separate forms, and two separate menu entries. The existing 'Amplicon' menu entry will need to be renamed to '16S' to more accurately reflect the existing form.