Mariobros

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- Nothing changed yet.

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- Add a `--port` command line option to select the port the scheduler listen to.

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- Fixed a couple of string Python2/3 bugs.

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- Change default Mako filter to pretty print iterables.
- Add IMPORT_MODULES variable to import modules in the template namespace.

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- All special variable in mariofile are now uppercase.
- Add support for SHELL variable.