Blender Git Loki

Fix various issues with temporary, maximized File Browsers

If Preferences > Interface > Temporary Editors > File Browser is set to
"Maximized Area", opening a File Browser from a File or Asset Browser as
regular editor would cause some issues. For example after closing the
temporary File Browser, the regular browser would take over the file
path and display settings from the temporary one. This is because they
used to share the same area data.

Some similar issues may have happend with temporary image editors.

Now, this commit finally separates the space data of temporary maximized
editors from the regular ones. So the editor data is entirely
independent now, as it should be.