Improved files uploading to automatically choosen location

*Title: Improved files uploading to automatically choosen location.

*Incentive:

There is a setting that allows to set rules for automatic location selection
when uploading files (for example in the "Insert object" dialog of Online Editor).

content.ini:[RelationAssignmentSettings].ClassSpecificAssignment

Each line of this array contain class identifier and locations list.
(see content.ini comments for details)

But if current user has no access to any of locations in the matched list,
file will not be uploaded. This is not handy in case when different users
have their own folders for uploading files and want to use "Automatic"
feature when uploading.

*Documentation:

From version 3.9 it is possible to specify the same class name in more than one line.
In this case the system will go through all matched lines and choose a line that
contain locations where user has 'create' access rights.

If there is more then one such line, the first one will be used.

*Example:

Let's say some user has no access to the folder 'media/images' but has access to
the folder 'media/myfolder'. In this case if he/she will upload an image, and
select "Automatic" option in the "Location" dropbox of the file upload dialog,
then a folder 'media/myfolder' will be automatically choosen.

ClassSpecificAssignment[]
ClassSpecificAssignment[]=image;media/images
ClassSpecificAssignment[]=image;media/myfolder