Bash completion updates. A few extracted from issue 2042, most as a result of running bash_completion_test.
Bash completion updates. A few extracted from issue 2042, most as a result of
running bash_completion_test.

* tools/client-side/bash_completion: Update comments - we want to avoid
    mentioning command abbreviations which are purely prefixes of others,
    regardless of whether they are unambiguous or not.
  (_svn): Add --ignore-externals.
  (_svnadmin): Remove "h", which overlapped "hotcopy". "$qOpts" isn't defined
    here, so expand to the intended text in its one use case.
    Add "rmtxns --quiet" and "setlog --bypass-hooks".

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion