remove duplicated config initialization

case insensitive for section and key for ini config

there is no need to check if b.params is nil

update logic for check ini comments

if iniconf.String("demo.key1") != "asta" {
+		t.Fatal("get demo.key1 error")
+	}
+	if iniconf.String("demo.key2") != "xie" {
+		t.Fatal("get demo.key2 error")
+	}

add server host:port info when starting app

beego.Context.Abort return immediately

* add common 4XX/5XX HTTP exceptions

add function InsertFilter to replace AddFilter by using int const to determine filter position

pos can be const:
    BeforeRouter = iota
    AfterStatic
    BeforeExec
    AfterExec
    FinishRouter

[orm] QueryTable with nil ptr struct

http.ResponseWriter doesn't implement  WriteCloser interface

The removed code will never be executed, remove it