ACG Matrix3x3T: add getRow() and getCol() convenience getters

libs_required/ACG/Math/Matrix3x3T.hh

@@ -95,6 +95,13 @@ class Matrix3x3T {
             return values_[i];
         }
 
+        Vec3 getRow(uint_fast8_t r) const {
+            return Vec3((*this)(r,0), (*this)(r,1), (*this)(r,2));
+        }
+        Vec3 getCol(uint_fast8_t c) const {
+            return Vec3((*this)(0,c), (*this)(1,c), (*this)(2,c));
+        }
+
         constexpr Matrix3x3T operator*(const Matrix3x3T &rhs) const {
             return Matrix3x3T {{
                 (*this)(0, 0) * rhs(0, 0) + (*this)(0, 1) * rhs(1, 0) + (*this)(0, 2) * rhs(2, 0),