Fix replacement of separator chars on Windows

Backslashes are special when used in a replacement string. 
See the documentation of java.util.regex.Matcher.replaceAll(String) for details.
java.util.regex.Matcher.quoteReplacement(String) fixes backslashes so
they can be replaced verbatim.
Merge pull request #17 from smee/patch-1

Fix replacement of separator chars on Windows