SLA optimized parametric DuPont Shell

This is a remix of [full parametric DuPont Shell](https://www.thingiverse.com/thing:4828731) with few additions for good printability in SLA printers and few modifications:
* Parameter naming changed a little by using `columns` instead of `Two_Lines`
* dedicated SLA supports are generated with `SLA_supports` switch with additional tuning parameters (needle diameter, pitch)
* latch has been shortened a bit, as the previous design seems to be too tight and sometimes did not engage
* latch size inside was increased with `latch_thickness` parameter, otherwise connector won't stay
* wall size increased and is parameteric
* dimension were slightly fixed
* pin chamfering increased
* possibility to print without the support directly on the bed: In this case outlets should be enabled via `Outlet_dia` parameterer. This helps slightly with the flow of resin during printing and later with cleaning. I do not recommend to use this, as the elephant foot compensation is difficult to control with such