Fix usage of uninitialized BBox.

src/dsc.h

@@ -498,8 +498,7 @@ public:
     Vector minp;
     Vector maxp;
 
-    BBox();
-    BBox(const Vector &p0, const Vector &p1);
+    static BBox From(const Vector &p0, const Vector &p1);
 
     Vector GetOrigin();
     Vector GetExtents();

src/solvespace.cpp

@@ -819,7 +819,7 @@ void Sketch::Clear(void) {
 }
 
 BBox Sketch::CalculateEntityBBox(bool includingInvisible) {
-    BBox box;
+    BBox box = {};
     bool first = true;
     for(int i = 0; i < entity.n; i++) {
         Entity *e = (Entity *)&entity.elem[i];

src/util.cpp

@@ -1015,15 +1015,16 @@ bool Point2d::Equals(Point2d v, double tol) const {
     return (this->Minus(v)).MagSquared() < tol*tol;
 }
 
-BBox::BBox() { }
-BBox::BBox(const Vector &p0, const Vector &p1) {
-    minp.x = min(p0.x, p1.x);
-    minp.y = min(p0.y, p1.y);
-    minp.z = min(p0.z, p1.z);
+BBox BBox::From(const Vector &p0, const Vector &p1) {
+    BBox bbox;
+    bbox.minp.x = min(p0.x, p1.x);
+    bbox.minp.y = min(p0.y, p1.y);
+    bbox.minp.z = min(p0.z, p1.z);
 
-    maxp.x = max(p0.x, p1.x);
-    maxp.y = max(p0.y, p1.y);
-    maxp.z = max(p0.z, p1.z);
+    bbox.maxp.x = max(p0.x, p1.x);
+    bbox.maxp.y = max(p0.y, p1.y);
+    bbox.maxp.z = max(p0.z, p1.z);
+    return bbox;
 }
 
 Vector BBox::GetOrigin() { return minp.Plus(maxp.Minus(minp)).ScaledBy(0.5); }