support the optional return char in version.txt (added by github editor) (#370)

CMakeLists.txt

@@ -10,7 +10,7 @@ endif()
 function(read_version_file major_var minor_var patch_var)
   set(version_file ${PROJECT_SOURCE_DIR}/version.txt)
   file(READ ${version_file} version_file_content)
-  if(version_file_content MATCHES "^([0-9]+)\\.([0-9]+)\\.([0-9]+)$")
+  if(version_file_content MATCHES "^([0-9]+)\\.([0-9]+)\\.([0-9]+)[\n]?$")
     set(${major_var} ${CMAKE_MATCH_1} PARENT_SCOPE)
     set(${minor_var} ${CMAKE_MATCH_2} PARENT_SCOPE)
     set(${patch_var} ${CMAKE_MATCH_3} PARENT_SCOPE)