Allow "raw" output, not wrapped in "<results>"

[bkmeneguello]

When ... | xq "//some/node/text()" the output is:

<results>
  <result>sometext</result>
</results>

Should exist an option, like -r/--raw to output text only.

This is important because it prevents piping the output directly to the next command

[nozhT]

This pull request seems to do that