RoundedTriangleEdge: Reduce default height to 50

Avoid height of several generators becoming negative if
RoundedTriangleEdge is selceted with default values e.g. for
UniversalBox and TypeTray. These are only 100mm hight with outside
option being enabled.

Thanks to https://github.com/SuksAE, https://github.com/HaSHsss and
https://github.com/Arcturuss for pushing this issue.

Resolves: #406
Resolves: #305

boxes/edges.py

@@ -2356,7 +2356,7 @@ Values:
 """
 
     absolute_params = {
-        "height" : 150.,
+        "height" : 50.,
         "radius" : 30.,
         "r_hole" : 2.,
     }