Update textobj-user and textobj-function.

You probably haven't seen the email yet, but someone complained about getting an error message in textobj-user in their setup--especially when run in verbose mode.  They attempted to solve the problem by upgrading textobj-user and textobj-function, and removing textobj-rst.  Unfortunately, that solution alone didn't fix the issue--at least not correctly.  The real issue is that when setting the `sfile` for a plugin, the `snr_prefix` function in textobj-user redirects and captures `scriptnames`.  In verbose mode, this redirect will also contain log messages, which is why there was a failure--the match list would end up being empty and the code would still attempt to access it.  So I proposed a fix to kana, who as usual, had another way of solving the problem.  He also released a new version of textobj-user with the fix.  This PR incorporates that version, along with an update textobj-function.