Small fix for a possible crash in divelist.c

divelist.c:copy_tree_node():
pass the pointer "icon" to gtk_tree_store_set()

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
windows.c: Add unicode support in subsurface_launch_for_uri()

subsurface_launch_for_uri() requires unicode support, using
ShellExecuteW() and also the passed UTF-8 buffer has to be translated
to UTF-16 beforehand. Once the ShellExecuteW() is done we release
the UTF-16 allocation.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>