Add tasks for all the new languages

Task/Caesar-cipher/ERRE/caesar-cipher.erre

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+PROGRAM CAESAR
+
+!$INCLUDE="PC.LIB"
+
+PROCEDURE CAESAR(TEXT$,KY%->CY$)
+    LOCAL I%,C%
+    FOR I%=1 TO LEN(TEXT$) DO
+      C%=ASC(MID$(TEXT$,I%))
+      IF (C% AND $1F)>=1 AND (C% AND $1F)<=26 THEN
+        C%=(C% AND $E0) OR (((C% AND $1F)+KY%-1) MOD 26+1)
+        CHANGE(TEXT$,I%,CHR$(C%)->TEXT$)
+      END IF
+    END FOR
+    CY$=TEXT$
+END PROCEDURE
+
+BEGIN
+    RANDOMIZE(TIMER)
+    PLAINTEXT$="Pack my box with five dozen liquor jugs"
+    PRINT(PLAINTEXT$)
+
+    KY%=1+INT(25*RND(1))  ! generates random between 1 and 25
+    CAESAR(PLAINTEXT$,KY%->CYPHERTEXT$)
+    PRINT(CYPHERTEXT$)
+
+    CAESAR(CYPHERTEXT$,26-KY%->DECYPHERED$)
+    PRINT(DECYPHERED$)
+
+END PROGRAM