fix to exhume key (steg) to correctly print on stdout when -k -

addressing issue #118

tomb

@@ -942,7 +942,10 @@ bury_key() {
 }
 exhume_key() {
     tombkey="`option_value -k`"
-    { test "$tombkey" = "" } && { tombkey=stdout }
+    { test "$tombkey" = "" } && {
+        tombkey="-"
+        _message "printing exhumed key on stdout"
+    }
 
     imagefile="$1"
     res=1
@@ -952,6 +955,7 @@ exhume_key() {
         _failure "Encode failed: $imagefile is not a jpeg image."
     fi
 
+    { test "$tombkey" = "-" } || {
         if [[ -e "$tombkey" ]]; then
             _warning "File exists: $tombkey"
             { option_is_set -f } || {
@@ -960,6 +964,7 @@ exhume_key() {
             _warning "Use of --force selected: overwriting."
             rm -f ${tombkey}
         fi
+    }
 
     _message "Trying to exhume a key out of image $imagefile"
     if option_is_set --tomb-pwd; then