Utility for checking the encoding and line ending of source files (#5188)

* Add utility for checking the encoding of source files

- accept source files with ASCII or UTF-8 without BOM
- accept only CRLF line ending

* Fix non-ascii symbol in idl_parcer.cpp

* Remove BOM from test.cpp

.travis.yml

@@ -89,6 +89,7 @@ matrix:
       - if [ "$TRAVIS_OS_NAME" == "linux" ]; then sudo ln -s -v -f $(which gcc-$GCC_VERSION) /usr/bin/gcc; fi
 
       script:
+      - bash .travis/check-sources.sh
       - bash grpc/build_grpc.sh
       - cmake . 
         -DCMAKE_BUILD_TYPE=$BUILD_TYPE