Add Echolisp, Realbasic, Rebol, Retro, Rtl2 and Xlisp

Fixes: #533
Co-Authored-By: Alexander von Recum <avrecum@users.noreply.github.com>

r/rtl2.rtl2

@@ -0,0 +1,12 @@
+TITLE Hello World;
+
+LET NL=10;
+
+EXT PROC(REF ARRAY BYTE) TWRT;
+
+ENT PROC INT RRJOB();
+
+    TWRT("Hello World#NL#");
+    RETURN(1);
+
+ENDPROC;