Steven, Nico

How to handle dependencies:

1) Add --require parameter for all types
   - Special handling in cdist-type-emulator
   + Everything on one line

2) Add __require type
   + No change in core
   - Type influences core
   - Additional line
   - Core needs to know about requirements

3) cdist-require as a seperate executable
   + No change in cdist-type-emulator
   - new behaviour
   - first time cdist-xxx dependency in types

4) require="" environment variable for cdist-type-emulator
   + on one line / same context
   + special handling is ok for special case
   + doesn't touch parameters (i.e. type still has full control)

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Result: Use version 4.
