Added new special operators like &= and <<=.

Also made a litle change to scanner function moveOn(): now it moves on
the last char passed and only if there are more than one chars.

t_list_test.go

@@ -38,9 +38,9 @@ func TestListParser(t *testing.T) {
 		/*  24 */ {`["a","b","c","d"][1]`, "b", nil},
 		/*  25 */ {`["a","b","c","d"][1,1]`, nil, `[1:19] one index only is allowed`},
 		/*  26 */ {`[0,1,2,3,4][:]`, newListA(int64(0), int64(1), int64(2), int64(3), int64(4)), nil},
-		/*  27 */ {`["a", "b", "c"] << ;`, nil, `[1:18] infix operator "<<" requires two non-nil operands, got 1`},
+		/*  27 */ {`["a", "b", "c"] <+ ;`, nil, `[1:18] infix operator "<+" requires two non-nil operands, got 1`},
 		/*  28 */ {`2 << 3;`, int64(16), nil},
-		/*  29 */ {`but >> ["a", "b", "c"]`, nil, `[1:6] infix operator ">>" requires two non-nil operands, got 0`},
+		/*  29 */ {`but +> ["a", "b", "c"]`, nil, `[1:6] infix operator "+>" requires two non-nil operands, got 0`},
 		/*  30 */ {`2 >> 3;`, int64(0), nil},
 		/*  31 */ {`a=[1,2]; a<+3`, newListA(int64(1), int64(2), int64(3)), nil},
 		/*  32 */ {`a=[1,2]; 5+>a`, newListA(int64(5), int64(1), int64(2)), nil},