Guys I guess I found THE solution for image upload.
It's a solution the website postimage.org offers.
Go to:
1. http://postimage.org/
2. add image hosting to your forum
3. Select your language
4. Select software, choose phpbb3.
5. Put the addform.html in root folder
After that, you will need to edit addform.html file a bit
Change this line:
var area_e=opener.document.getElementsByTagName('TEXTAREA');
to:
var area_e=opener.document.getElementId('a_content');
After this, you will need to add this link:
<br /> • <a href="javascript:void(0);" onclick="window.open('http://www.postimage.org/index.php?mode=phpbb&lang=english&forumurl=' + escape(document.location.href), '_imagehost', 'resizable=yes,width=500,height=400');return false;">Add image to post</a>
Somewhere near your editor.
I still haven't figured out where, neither tested the tutorial abovem but you get the idea.
I will keep this topic updated when I'm totally done implementing this.
Something yet needs to be done: q2a recognizing img and link elements and allowing them to show up as a linked image.