`-#`/`--shift` option no longer seems to work

[jaminthorns]

Ever since upgrading from less-643 to less-661, I noticed that the -#/--shift option no longer seems to have any effect, and instead the default value of .5 is used. The functionality still works properly as I can set the option from within less with the -- command.

Steps to Reproduce

• Run this command in a POSIX shell:

  for i in (seq 1 $COLUMNS); echo -n X; end | less --shift=.1
  

• Hit the → (right arrow) key once.

• Notice that the screen moves by 1/2 the screen width instead of 1/10 width as specified.