Hardcoded call in edition engine to a file defined in templates

503 r18749

Since commit 779 (corpV2, 50-SP branch), css/ template_css.xml has been added.
The problem is that this file is loaded when FCK is displayed, and causes an error if missing. So, when importing the online demo (with old templates), this file is missing. It will be so for customers who upgrade SP2 to SP3.
I don't know what is the better solution, maybe defining default values which we can overwrite in this file, which can be missing without causing any error. (in this case add a DOCU entry so that we don't forget to document in template developer guide that this file can be defined).
Maybe the same problem with css/blog_css.xml, also added in same commit