Fix clipdel escaped only first '#'

[Gravemind]

Clipdel only escapes the first '#'. Repro steps:

• copy and run clipdel '#foo#', you get:

  sed: -e expression #1, char 9: comments don't accept any addresses
  

This PR fix this by using bash expansion subtlety, from bash reference:

${parameter/pattern/string}
... If pattern begins with ‘/’, all matches of pattern are replaced with string...

[cdown]

Well, that's a fuckup. Thanks!

[cdown]

(in general I hope #78 will help find these faster in future)