Add debug messages to show in notification box

Rename show_notifybox() to add_to_notifybox() to use a more meaningful
name.

OOMAnalyser.html

@@ -202,15 +202,21 @@ THIS PROGRAM COMES WITH NO WARRANTY
             word-wrap: break-word;
         }
 
-        .js-notify_box__msg--warning {
+        .js-notify_box__msg--debug {
-            color: #9F6000;
+            color: #000000;
-            background-color: #FEEFB3;
+            background-color: #e8ffb3;
         }
+
         .js-notify_box__msg--error {
             color: #D8000C;
             background-color: #FFD2D2;
         }
 
+        .js-notify_box__msg--warning {
+            color: #9F6000;
+            background-color: #FEEFB3;
+        }
+
         .license__text {
             font-size: small;
         }

OOMAnalyser.py

@@ -183,27 +183,39 @@ def escape_html(unsafe):
     )
 
 
+def debug(msg):
+    """Add debug message to the notification box"""
+    add_to_notifybox("DEBUG", msg)
+
+
 def error(msg):
-    """Show the error box and add the error message"""
+    """Show the notification box and add the error message"""
-    show_notifybox("ERROR", msg)
+    add_to_notifybox("ERROR", msg)
 
 
 def internal_error(msg):
-    """Show the error box and add the internal error message"""
+    """Show the notification box and add the internal error message"""
-    show_notifybox("INTERNAL ERROR", msg)
+    add_to_notifybox("INTERNAL ERROR", msg)
 
 
 def warning(msg):
-    """Show the error box and add the warning message"""
+    """Show the notification box and add the warning message"""
-    show_notifybox("WARNING", msg)
+    add_to_notifybox("WARNING", msg)
 
 
-def show_notifybox(prefix, msg):
+def add_to_notifybox(prefix, msg):
-    """Show escaped message in the notification box"""
+    """
-    if prefix == "WARNING":
+    Escaped and add message to the notification box
+
+    If the message has a prefix "ERROR" or "WARNING" the notification box will be shown.
+    """
+    if prefix == "DEBUG":
+        css_class = "js-notify_box__msg--debug"
+    elif prefix == "WARNING":
         css_class = "js-notify_box__msg--warning"
     else:
         css_class = "js-notify_box__msg--error"
+    if prefix != "DEBUG":
         show_element("notify_box")
     notify_box = document.getElementById("notify_box")
     notification = document.createElement("div")