added .DS_Store to gitignore
extended vicotool to create a new document from stdin if first filename is "-"

example usage:
ls -l | vicotool -
refactored duplicate backChannel communication to its own method

and don't set the close callback if backChannel is nil
updated vicotool usage text
Merge pull request #32 from stifal/vicotool-read-stdin

Add option to vicotool to create a new document with text from stdin

Syntax is using a - instead of a filename:
 $ ls -l | vicotool -