• track $TERM for the types tmux uses /^screen(-.*)?$/
• when tmux is in use (or GNU screen, really), use the, now
hardcoded, clear-to-EOL string; otherwise, use the old behaviour
• drop unnecessary x_e_rebuildline()
carefully tested to behave no worse than R52b
to it are now either arc4random or rand/srand, but srand retains the old
state; set +o arc4random is no longer possible, but if it's there we use
arc4random(3), if not, we use rand(3) for $RANDOM reads; optimise special
variable handling too and fix a few consts and other minor things
