Rely toEqualFile fails on trailing newline

[ng-marcus]

I'm using rely to test the output of a program (captured as a string) against the content of a file.

The test fails because the string ends with a newline but the file is read in with the final newline ignored. (My test file is a single line, ending in a newline)

I believe this is because of this implementation in Rely.IO

let readFile = (file: string): string => String.concat("\n", readLines(file));

I'm happy to make a PR to fix this, but just wanted to check this is not intentional behaviour.

[bandersongit]

Definitely not intentional, a PR would be appreciated!