Added priority condition

FAQ.md

@@ -2624,6 +2624,8 @@ $$replydomain$
 $$nofrom$ (since version 1.1791)
 $$multifrom$ (since version 1.1791)
 $$automatic$ (since version 1.1862)
+$$lowpriority (since version 1.1958)
+$$highpriority (since version 1.1958)
 ```
 
 Note that *regex* should be disable and that there should be no white space.

app/src/main/java/eu/faircode/email/EntityRule.java

@@ -306,6 +306,12 @@ public class EntityRule {
                     } else if ("$automatic".equals(keyword)) {
                         if (!Boolean.TRUE.equals(message.auto_submitted))
                             return false;
+                    } else if ("$lowpriority".equals(keyword)) {
+                        if (!EntityMessage.PRIORITIY_LOW.equals(message.priority))
+                            return false;
+                    } else if ("$highpriority".equals(keyword)) {
+                        if (!EntityMessage.PRIORITIY_HIGH.equals(message.priority))
+                            return false;
                     } else {
                         List<String> keywords = new ArrayList<>();
                         keywords.addAll(Arrays.asList(message.keywords));