Fix #210 TileMaps: Allow reading in of native external tsx files
Fix #210 TileMaps: Allow reading in of native external tsx files

TukekeSoft/CocosSharp,MSylvia/CocosSharp,zmaruo/CocosSharp,TukekeSoft/CocosSharp,mono/CocosSharp,haithemaraissia/CocosSharp,zmaruo/CocosSharp,mono/CocosSharp,MSylvia/CocosSharp,haithemaraissia/CocosSharp