move Inc() to Incr()

engine.go

@@ -358,10 +358,10 @@ func (engine *Engine) In(column string, args ...interface{}) *Session {
 }
 
 // Method Inc provides a update string like "column = column + ?"
-func (engine *Engine) Inc(column string, arg interface{}) *Session {
+func (engine *Engine) Incr(column string, arg ...interface{}) *Session {
 	session := engine.NewSession()
 	session.IsAutoClose = true
-	return session.Inc(column, arg)
+	return session.Incr(column, arg...)
 }
 
 // Temporarily change the Get, Find, Update's table

session.go

@@ -129,8 +129,8 @@ func (session *Session) In(column string, args ...interface{}) *Session {
 }
 
 // Method In provides a query string like "count = count + 1"
-func (session *Session) Inc(column string, arg interface{}) *Session {
+func (session *Session) Incr(column string, arg ...interface{}) *Session {
-	session.Statement.Inc(column, arg)
+	session.Statement.Incr(column, arg...)
 	return session
 }
 

statement.go

@@ -473,9 +473,13 @@ func (statement *Statement) Id(id interface{}) *Statement {
 }
 
 // Generate  "Update ... Set column = column + arg" statment
-func (statement *Statement) Inc(column string, arg interface{}) *Statement {
+func (statement *Statement) Incr(column string, arg ...interface{}) *Statement {
 	k := strings.ToLower(column)
-	statement.incColumns[k] = arg
+	if len(arg) > 0 {
+		statement.incColumns[k] = arg[0]
+	} else {
+		statement.incColumns[k] = 1
+	}
 	return statement
 }