Added $$signed$ and $$encrypted$ conditions

FAQ.md

@@ -2660,6 +2660,8 @@ $$multifrom$ (since version 1.1791)
 $$automatic$ (since version 1.1862)
 $$lowpriority$ (since version 1.1958)
 $$highpriority$ (since version 1.1958)
+$$signed$ (since version 1.1981)
+$$encrypted$ (since version 1.1981)
 ```
 
 Note that *regex* should be disable and that there should be no white space.

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

@@ -312,6 +312,12 @@ public class EntityRule {
                     } else if ("$highpriority".equals(keyword)) {
                         if (!EntityMessage.PRIORITIY_HIGH.equals(message.priority))
                             return false;
+                    } else if ("$signed".equals(keyword)) {
+                        if (!message.isSigned())
+                            return false;
+                    } else if ("$encrypted".equals(keyword)) {
+                        if (!message.isEncrypted())
+                            return false;
                     } else {
                         List<String> keywords = new ArrayList<>();
                         keywords.addAll(Arrays.asList(message.keywords));