add proxy to show image/vedio out of the webserver root directory

[imcraftsman]

when we login as an ordinary client, our folders which assigned by the administrator are usually not in the webserver root directory. so, we could not get the file's hyperlink, and we could not preview pictures and appreciate video online. but,now,the problem is solved when a proxy is added in tinyfilemanager.php. modified items list:

1. add a proxy;
2. modify image's/video's hyperlinks
3. modify file's 'direct link' related with open button.

in addition: There is a clerical error in lin "$fileTypes['jfif'] = 'image/jpg';" it should be "$fileTypes['jfif'] = 'image/jfif';" in my another PR(PR id= #1269)

[imcraftsman]

this PR relate to these issues: Preview images and direct links not working for user specific directories #724 https://github.com/prasathmani/tinyfilemanager/issues/724 Cannot play mp3 #1146 https://github.com/prasathmani/tinyfilemanager/issues/1146 File preview and opening not working. #1247 https://github.com/prasathmani/tinyfilemanager/issues/1247