I did as you recommended to clear up the old loops, although I could not pinpoint to a specific direction that explained why I was getting the loops. I disabled directions, then deleted them completely and even disabled Redirection but still I was getting the loops again.
Somehow, I thought, there should be a way of clearing the memory of wordpress for the name changes I made and it seemed unrealistically complicated to work on the codes for such a simple thing. In the forums people were advising each other to make several code changes, referring to rewriting of .htaccess or the codes of the theme but I was afraid to do them as I could have totally cause a serious crash.
But finally after spending almost three days in desperation, and also suspecting that it might be related with my WordPress SEO plugin (as it sets the way your pages will be named according to your choise) I solved the problem :-)) And-as I suspected, it was extremely simple.
I am explaining the steps so that others who have a similar problem may solve their problem too. (unless of course their problem is related to another aspect of the problem.)
For me, the problem started when I rechanged the title of a page to the very firts title I used i.e.to http://www.trade-gate.net/eurostrong-televizyon-koltuklari/ from http://www.trade-gate.net/masaj-koltugu/. Afterwards, when I wanted to access this new page, I was getting an error saying that I have a "redirection loop"
I then started checking everything on my page and on the WordPress SEO plugin that has a system for automatically setting the way page titles will be formed, I realised that my new page's "page short name" was remaining as masaj-koltuklari whereas the slug of the page became eurostrong-televizyon-koltuklari when I changed the title.
When I corrected the page short name so that it would became the same as the page slug, the loop problem simply disappeared. I made the same change for 6-7 other pages that I had redirection loop problem with and it worked for them too. Now I do not have a loop anymore.
:-))) I am so happy.
I already made the change on the redirection.php file that you proposed above, so I am not sure whether my problem could have been solved without this change or not, but still I would like to thank you very much for your assistance. :-)
Have a nice day.