don't scan the whole file in case of proper line endings

might lead to strange behavior if people randomly distribute CRs in
their file. But that actually deserves to get strange behavior
+ Test

PRIVATE

@@ -1 +1 @@
-Subproject commit d90babadfb0a33afa1b793044cc4efd4d7430731
+Subproject commit 5d27d879abaeb1542e3f9f3065172be740af2899

src/IO.f90

@@ -124,7 +124,9 @@ function IO_read(fileName) result(fileContent)
   integer ::  &
     fileLength, &
     fileUnit, &
-    myStat
+    myStat, &
+    firstEOL
+  character, parameter :: CR = achar(13)
 
 
   inquire(file = fileName, size=fileLength)
@@ -141,10 +143,12 @@ function IO_read(fileName) result(fileContent)
   if(myStat /= 0) call IO_error(102,ext_msg=trim(fileName))
   close(fileUnit)
 
-  if(scan(fileContent,achar(13)) /= 0) call IO_error(115)
 
   if(fileContent(fileLength:fileLength) /= IO_EOL) fileContent = fileContent//IO_EOL                ! ensure EOL@EOF
 
+  firstEOL = index(fileContent,IO_EOL)
+  if(scan(fileContent(firstEOL:firstEOL),CR) /= 0) call IO_error(115)
+
 end function IO_read