Minor improvements

I've added code to strip HTML tags and unescape HTML entities before printing the result.
For example, now `ddg python print` outputs

    findertools.Print(file) Tell the finder to print a file. The behaviour is identical to selecting the file and using the print command in the finder’s file menu.

Instead of

    <pre><code>findertools.Print(file)</code></pre> Tell the finder to print a file. The behaviour is identical to selecting the file and using the print command in the finder&#8217;s file menu.

Also I've removed ugly exception handling from print_result and implemented proper content encoding in `search()`.