Some bugs

Hi,

I found some bugs I think.

1. ROX saves calculated display_style as a current display setting.
It is not a user's setting. I think it should be display_style_wanted. 
Like this:
https://github.com/jun7/rox-filer/commit/5e56c609c3374436bc5f394c6d8b031e96d64378

2. Lack of convert to realpath in the code creating relative sym links.
Even the `from' contains links, the code generating relative path doesn't care it. 

3. Window auto-move of the auto-resize points wrong coordinate.
It doesn't contain window decoration.
In fluxbox and openbox, ROX wills slide down because of it.

4. Relating 3, most window managers manage the behavior of re-size
by their own role and they knows docks and taskbars.
So it should be left for window managers.

I've tried to fix 3 and 4 like this:
https://github.com/jun7/rox-filer/commit/13728647e0a5215013a8456732be6c8b33008923

In addition, I've made some other changes too. could I send pull request?



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