annotate: pack line content into annotateline object (API)
Just for code readability. We can do that since the annotateline type is
no longer used while computing the history.
pager.pager=p0 # $TESTTMP/sysrc:4
ui.editor=e1 # $TESTTMP/userrc:2
pager.pager=p2 # $PAGER
ui.editor=e1 # $TESTTMP/userrc:2