Separate test results with diags
Test empty sequences at the end are properly flushed (they are)
Test the --filename-key bug fixed in 61f948d

This test fails before the fixing commit and passes now.
Avoid extra trailing newlines for sequences without any bases

push_line() always adds a newline, so we can safely chomp any newline
before pushing the line out.

Silences an uninitialized warning when there's no bases too.
Tests for recs-tofasta
0.09