emacsclient and sublimity cause error

[michaelcadilhac]

I wrongly reported that upstream:

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=65877

(See therein for a way to reproduce bug.)

The code (line-number-at-pos (window-start)) appears a couple times in Sublimity, and it should be changed, throughout, to be encapsulated in (with-current-buffer (window-buffer) …).