Do not add the module separator indiscriminantly

[HalosGhost]

At the moment, a module separator is baked into each module's format string. The end result is that, if you disable modules at compile time, you can end up with an unnecessary separator.

This is quite simple to fix. Remove the baked-in separator from each module. Between each module write, check if something has been written to the buffer for output. If so, add the module separator.

[HalosGhost]

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