Fix : Close Preview Window after insertion.

Fixes #524

**I signed the CLA.**

After doing a bit of history research, I came to the conclusion that `s:searched_and_results_found` was actually used to prevent an infinite loop.
Although, the de8f45c2021814529928c5025ce08ffb6b47cb6f commit changed this. The only purpose of the `s:searched_and_results_found` variable now was to avoid calling `pclose` if there were no results.

Now, this condition is only causing trouble. Calling `pclose` whether there are results or not is not a problem.

So in the end, I've found no reason anymore for this condition, unless @Valloric says otherwise, so we can simply remove it, and the `s:searched_and_results_found` variable too.