- fix displaying/refreshing desktop icons in category view

[common.c]
- comply with http://www.freedesktop.org/wiki/Specifications/XDND:
  * the target should be "text/uri-list"
  * filenames should be prepended with "file:///"
  * how is this supposed to handle multiple filenames then? "\r\n"?
- implement XDS: http://www.newplanetsoftware.com/xds/

[copy.c]
- browse sub-directories when idle
- copy files when data is available

[desktop.c]
- enable drag and drop as a source

[properties.c]
- resolve relative paths
- add an option to count files altogether

[view.c]
- load text files progressively
- add an option to force a file type
