POSIX leaves undefined the order of output if stderr is injected into stdout,
and in practice it differs on Windows (Linux buffers both streams separately,
Windows interleaves them as they arrive without buffering).
This should help testing on other platforms
Previously, a PUSHS before a SECTION directive would cause rgbasm to crash when encountering a subsequent POPS.
This is because the subsequently-called out_setCurrentSection() expected the new section to be non-null, which wasn’t the case in this situation. This has been addressed by allowing the ‘null’ section to be set in this function, and only dereferencing it (to set nPC) if a non-null section is to be set.
In practice, this means that PUSHS/POPS can now be used to push/restore a context without a section.
