--max-iterations N should not exit with error status

[dandavison]

When I specify --max-iterations N, my sense is that, if the document compiles without error over the N iterations, then latexrun should exit with process exit code 0, regardless of whether the iterations have converged to stability. I.e. I have asked it to run N times, presumably because I was prepared to accept non-convergence, and it did so successfully, so that should be success. However, latexrun exits with an error status and an error message. I suggest this should be a warning message and success status.

$ cat z.tex 
\documentclass{article}
\begin{document}
hello
\end{document}

$  latexrun z.tex && echo $?
0

$ latexrun --max-iterations 1 z.tex ; echo $?
error: files are still changing after 1 iterations; giving up
1