Introduce more local imports.
Clean up logging module.

Also add some pure / nothrow / @safe where applicable.
Not many functions can use it because most use write(f)ln eventually.
Improve parallel helper functions.
Add annotations to functions in parameters.d.

Also some minor whitespace changes and a debug bugfix.
Adding pure annotation placeholders that do not work with GDC.
Clean up mixinhelper.d.