Change window alert setting names and defaults

- Notifications.alert_time → Notifications.flash_time,
  more evocative of what these "alerts" actually do

- Change default for the above from 0 to 5, since now push rules already
  control precisely what to enable or disable these alerts for

- Notifications.urgent_alert_time → Notifications.highlight_flash_time,
  "highlight" is the term used in the matrix doc

docs/TODO.md

@@ -8,7 +8,6 @@
 - profiles missing in notifications
 - option to use plaintext notifications
 - Notification urgency level (plyer)?
-- Rename the alertOn(Mention/Message)ForMsec options, default Message to non-0
 - Make local unread counter an optional turned off by default
 
 - Implement fallback QML notifications, usable if dbus isn't available

src/config/settings.py

@@ -40,16 +40,18 @@ class Presence:
     auto_away_after: int = 60 * 10
 
 class Notifications:
-    # How long in seconds window alerts will last when a new message
-    # is posted in a room. On most desktops, this highlights or flashes the
-    # application in the taskbar or dock.
-    # Can be set to 0 for no alerts.
+    # How long in seconds the window will flash in your dock or taskbar when
+    # a new message, which matches a notification push rule with a
+    # flash (lightbulb) action, is posted in a room.
+    # The effect may differ depending on your OS/desktop.
+    # or dock to be highlighted or to flash.
     # Can be set to -1 for alerts that last until the window is focused.
-    alert_time: float = 0
+    flash_time: float = 5
 
-    # Same as alert_time for urgent messages, e.g. when you are mentioned,
-    # replied to, or the message contains a keyword.
-    urgent_alert_time: float = -1
+    # Same as flash_time, but for messages that match a push rule with a
+    # highlight (red [+1]) action. By default this includes when your
+    # name is mentioned, replied to, or messages containing keywords.
+    highlight_flash_time: float = -1
 
 class Scrolling:
     # Use velocity-based kinetic scrolling.

src/gui/PythonBridge/EventHandlers.qml

@@ -29,8 +29,8 @@ QtObject {
         if (urgencyHint) {
             const msec =
                 critical ?
-                window.settings.Notifications.urgent_alert_time * 1000 :
-                window.settings.Notifications.alert_time * 1000
+                window.settings.Notifications.highlight_flash_time * 1000 :
+                window.settings.Notifications.flash_time * 1000
 
                 // -1 ? 0 for no time out : msec
                 if (msec !== 0) window.alert(msec === -1 ? 0 : msec)