[A-1999] sbopkg - Revisions r866 to r876

rename get_sbo_packages() to list_packages()

change VARNAMES to VAR_NAMES

rename view_queue_readmes() to view_readmes()

generalize view_readmes()

create nvabt2n(); revise list_packages()

make list_packages() loop

modify list_packages() to preserve state, etc.

make remove_files() actually invert sel., etc.

modify view_queue() to use selection_state()

document gist of changes from r866-current

allow -Rp combo to page through all READMEs