Fix for the bugs 16075 and 16107

Bug: 16075
Bug: 16107

The following patch fixes bugs 16075 and 16107, i.e.
"Icon view: excess clickable area of multiline filenames" and
"Multi-line filenames misaligned when text beside icons is on"
respectively. By relying on gtk_cell_renderer_get_aligned_area and
gtk_cell_renderer_get_padding it brings the box[..].width and
box[..].height values into correspondence with the real size of
drawn text.

Signed-off-by: Sean Davis <smd.seandavis@gmail.com>