[WelcomeScreen.py] Added waiting in the fade out animation (missed that in an earlier commit)

Also improved memory usage a little bit by import the sleep method only, not the whole time library

WelcomeScreen.py

@@ -16,7 +16,7 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.
 """
 
-import time
+from time import sleep
 
 
 class WelcomeScreen:
@@ -100,7 +100,7 @@ class WelcomeScreen:
         self.lcd.move_to(0,y_offset)
         self.lcd.putstr(self.started_msg.center(16))
         
-        time.sleep(wait_after_cycles)
+        sleep(wait_after_cycles)
         
         # now fade down if enabled via the params
         if fade_down["enabled"]:
@@ -122,4 +122,5 @@ class WelcomeScreen:
                 old_display = old_display[:-self.columns]
                 lines_before = " " * (self.columns*self.lines-len(old_display))
                 self.lcd.putstr(lines_before + old_display)
-    
+                sleep(wait_between)
+            sleep(wait_after)