Remove deprecated 18/19/20 methods

This removes methods with the "18", "19", or "20" suffix
indicating that they are associated with those versions of Ruby.
Where there existed such methods that were not previously
deprecated, new deprecation was added but the methods were not
removed. Any remaining callers of these methods were modified to
call the non-suffixed version.

core/src/main/java/org/jruby/AbstractRubyMethod.java

@@ -77,11 +77,6 @@ public RubyFixnum arity() {
         return getRuntime().newFixnum(method.getSignature().arityValue());
     }
 
-    @Deprecated
-    public final IRubyObject op_eql19(ThreadContext context, IRubyObject other) {
-        return op_eql(context, other);
-    }
-
     @JRubyMethod(name = "eql?")
     public IRubyObject op_eql(ThreadContext context, IRubyObject other) {
         return RubyBoolean.newBoolean(context,  equals(other) );

core/src/main/java/org/jruby/RubyArgsFile.java

@@ -587,21 +587,11 @@ public static IRubyObject lines(ThreadContext context, IRubyObject recv, IRubyOb
         return each_line(context, recv, args, block);
     }
 
-    @Deprecated
-    public static IRubyObject each_line19(final ThreadContext context, IRubyObject recv, IRubyObject[] args, final Block block) {
-        return each_line(context, recv, args, block);
-    }
-
     @JRubyMethod(name = "each", optional = 1, checkArity = false)
     public static IRubyObject each(final ThreadContext context, IRubyObject recv, IRubyObject[] args, final Block block) {
         return block.isGiven() ? each_line(context, recv, args, block) : enumeratorize(context.runtime, recv, "each", args);
     }
 
-    @Deprecated
-    public static IRubyObject each19(final ThreadContext context, IRubyObject recv, IRubyObject[] args, final Block block) {
-        return each(context, recv, args, block);
-    }
-
     @JRubyMethod(name = "file")
     public static IRubyObject file(ThreadContext context, IRubyObject recv) {
         ArgsFileData data = ArgsFileData.getArgsFileData(context.runtime);