Allow paths with spaces in excluded directories list

[ju-kreber]

The list of excluded directories is space-separated and it seems like quoting path names with " or ' or escaping with \ doesn't have an effect. This is the behavior I would expect from the code
dirs_excluded = settings.value('directories_excluded').strip().split()

I know that really "parsing" the setting is some inconvenient work and so I'd like to suggest to check if the last character of a field (after split) is a \ and then just concatenate it with the next one and a space to allow at least the escaping approach.

However I have not looked deeper in the code how the results are used and if this would introduce some trouble elsewhere..