ren: allow arbitrary page number characters in .tl
fmt: fix scaledown()'s comment
wb: rename c_isdash() to c_dash()
tr: eos request to change end of sentence characters

The eos request expects two arguments:

  .eos sentchars transchars

In which sentchars is the list of sentence ending characters (.!?, by
default) and transchars is the list of characters ignored for
detecting the end of sentences ('"])*, by default).  Without any
arguments, the eos request disables detecting end of sentences.