modular ramps enclosure

aka the RAMPS-ratsnest-repressor :-)
for a prusa-i3 singleplate

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designed to meet the following requirements:

* mount and manage cables
* keep dust out
* extra space for small pcbs (voltage regulator, ...)
* allow airflow: use convection (bottom: cold air in, top: warm air out)
* fast and easy to print: flat pieces
* easy access: hinges everywhere! pull two hinge-pins and it opens up/unfolds
* "small" modules to easy customization and replacement of parts