ADDED: pack_property/2: readme(File) and todo(File) properties.  Used by doc_pack/1.
ADDED: pack_property/2: readme(File) and todo(File) properties.  Used
by doc_pack/1.

koryonik/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel