Add C# maker and upgrade the data to the latest 2020/10/31 release ve…

…rsion

ip2region 2.2.0 release version with source and binary data upgrade t…

…o version 2020/06/10

ip2region 2.1.0 release version with data partial upgrade to 2019/11/…

…11 version

ip2region 2.0.0 release version with data upgrade to version 2019/10/…

…27 and add Nginx plugin impl

ip2region 1.9.0 release version with java maker implementation and da…

…ta upgrade to version 2019/05/02

ip2region 1.8.0 release version with lua, lua_c binding and the data …

…upgrade to version 2018/12/31

Release version 1.7.0 with data upgrade to 2018/07/26 and rust bindin…

…g, some optimization

fix the region merge txt file & re-generate the ip2region.db file

Release version 1.6 with data update to 2018/03/26 and with c# bindin…

…g actived

release version 1.5 with data update to version 2018/01/12