tweak some shortcuts

aqt/main.py

@@ -1161,7 +1161,6 @@ It can take a long time. Proceed?""")):
         if sys.platform.startswith("darwin"):
             qt_mac_set_menubar_icons(False)
             self.setUnifiedTitleAndToolBarOnMac(True)
-            self.form.actionMarkCard.setShortcut(_("Alt+m"))
             # mac users expect a minimize option
             self.minimizeShortcut = QShortcut("Ctrl+m", self)
             self.connect(self.minimizeShortcut, SIGNAL("activated()"),

designer/main.ui

@@ -422,7 +422,7 @@
     <string/>
    </property>
    <property name="shortcut">
-    <string>Ctrl+M</string>
+    <string>M</string>
    </property>
   </action>
   <action name="actionSuspendCard">
@@ -609,7 +609,7 @@
     <string>Suspend the current fact until the deck is closed and opened again</string>
    </property>
    <property name="shortcut">
-    <string>Ctrl+Shift+B</string>
+    <string>Shift+B</string>
    </property>
   </action>
   <action name="actionFullDatabaseCheck">
@@ -684,7 +684,7 @@
     <string>Models...</string>
    </property>
    <property name="shortcut">
-    <string>Ctrl+M</string>
+    <string>Ctrl+Shift+M</string>
    </property>
   </action>
   <action name="actionDocumentation">