implement the "in" operator on slice with EqualValueTo() (#254)

It allows to make it work with different but equivalent types (e.g. int and int64).

Author: pierrre

template_tests/if.tpl

@@ -7,6 +7,7 @@
 {% if !simple.float %}false{% else %}!simple.float{% endif %}
 {% if "Text" in complex.post %}text field in complex.post{% endif %}
 {% if 5 in simple.intmap %}5 in simple.intmap{% endif %}
+{% if simple.uint in simple.multiple_item_list %}simple.uint in simple.multiple_item_list{% endif %}
 {% if !0.0 %}!0.0{% endif %}
 {% if !0 %}!0{% endif %}
 {% if not complex.post %}true{% else %}false{% endif %}

template_tests/if.tpl.out

@@ -7,6 +7,7 @@ float != 0.0
 !simple.float
 text field in complex.post
 5 in simple.intmap
+simple.uint in simple.multiple_item_list
 !0.0
 !0
 false

value.go

@@ -348,7 +348,7 @@ func (v *Value) Contains(other *Value) bool {
 	case reflect.Slice, reflect.Array:
 		for i := 0; i < v.getResolvedValue().Len(); i++ {
 			item := v.getResolvedValue().Index(i)
-			if other.Interface() == item.Interface() {
+			if other.EqualValueTo(AsValue(item.Interface())) {
 				return true
 			}
 		}