Correct `flexcomp` attribute types in schema.xml

[louisgevers]

Align the attribute types with the official documentation. Fixes the following errors:

• spacing's wrong conversion to int could lead to XML Error: Spacing must be larger than geometry size (e.g. 0.2 -> 0)
• Setting and edge's internal collisions to false leads to ValueError: Expect an integer value: got false (same for rigid attribute)