Prevent smoothState from overwriting himself

This prevents messing up pointers, looks a bit like this was an issue here:
https://github.com/weblinc/jquery.smoothState.js/issues/81
Fixed typo
Don't change default values

We don't want to alter the default options for future instances of the
plugin, so create a new object for the options.
Merge pull request #86 from rolandschuetz/master

Minor improvements