Add Configuration.RemoteAddrHeadersForce as requested at #1567 and change RemoteAddrHeaders from map to string slice

Read HISTORY.md entry

_examples/configuration/from-toml-file/configs/iris.tml

@@ -4,6 +4,6 @@ FireMethodNotAllowed = true
 DisableBodyConsumptionOnUnmarshal = false
 TimeFormat = "Mon, 01 Jan 2006 15:04:05 GMT"
 Charset = "utf-8"
-
+RemoteAddrHeaders = ["X-Real-Ip", "X-Forwarded-For", "CF-Connecting-IP"]
 [Other]
 	MyServerName = "iris"

_examples/configuration/from-yaml-file/configs/iris.yml

@@ -9,8 +9,8 @@ SSLProxyHeaders:
 HostProxyHeaders:
   X-Host: true
 RemoteAddrHeaders:
-  X-Real-Ip: true
-  X-Forwarded-For: true
-  CF-Connecting-IP: true
+  - X-Real-Ip
+  - X-Forwarded-For
+  - CF-Connecting-IP
 Other:
   Addr: :8080