Makes the script_load_addons test succeed in debug builds.
Add-ons may specify a big step size for large ranges, which would cause
a runtime RNA error in debug builds. The old validation logic was added in
The second hunk in this patch was needed for runtime RNA properties that
define a small range, e.g. MESH_OT_intersect.threshold. For them the
previous default step size of 0.01 didn't make sense at all, but didn't
error out. Now the step size maximum is softmax - softmin (we could
split that further but need to pay attention to precision issues with