allow passing in :line

[dehli]

👋 Hello! Thanks for all your work on this library! My reasoning for this PR is that I sometimes will add log/* to a macro. Inside of my macro, the &form is accessible however it's not accessible to log-expr in lambdaisland.glogi. This allows me to pass :line in as part of the macro and not have it overridden with nil. Thanks and let me know if you'd like any changes!