Set open target for force_tab to tab-silent

Fixes #1328

CHANGELOG.asciidoc

@@ -79,6 +79,8 @@ Changed
 - Counts can now be used with special keybindings (e.g. with modifiers).
   This was already implemented for v0.7.0 originally, but got reverted because
   it caused some issues and then never re-applied.
+- Sending a command to an existing instance (via "qutebrowser :reload") now
+  doesn't mark it as urgent anymore.
 
 Deprecated
 ~~~~~~~~~~

qutebrowser/mainwindow/mainwindow.py

@@ -67,7 +67,8 @@ def get_window(via_ipc, force_window=False, force_tab=False,
     if force_window:
         open_target = 'window'
     if force_tab and open_target == 'window':
-        open_target = 'tab'  # for lack of a better default
+        # Command sent via IPC
+        open_target = 'tab-silent'
 
     window = None
     raise_window = False