Cleanup: consistent use of tags: NOTE/TODO/FIXME/XXX

Also use doxy style function reference `#` prefix chars when
referencing identifiers.

source/blender/python/mathutils/mathutils_Color.c

@@ -68,7 +68,7 @@ static PyObject *Color_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 
 /* -----------------------------METHODS---------------------------- */
 
-/* note: BaseMath_ReadCallback must be called beforehand */
+/* NOTE: BaseMath_ReadCallback must be called beforehand. */
 static PyObject *Color_ToTupleExt(ColorObject *self, int ndigits)
 {
   PyObject *ret;

source/blender/python/mathutils/mathutils_Euler.c

@@ -110,7 +110,7 @@ short euler_order_from_string(const char *str, const char *error_prefix)
   return -1;
 }
 
-/* note: BaseMath_ReadCallback must be called beforehand */
+/* NOTE: BaseMath_ReadCallback must be called beforehand. */
 static PyObject *Euler_ToTupleExt(EulerObject *self, int ndigits)
 {
   PyObject *ret;

source/blender/python/mathutils/mathutils_Matrix.c

@@ -263,7 +263,7 @@ Mathutils_Callback mathutils_matrix_col_cb = {
 /* ----------------------------------------------------------------------------
  * matrix row callbacks
  * this is so you can do matrix.translation = val
- * note, this is _exactly like matrix.col except the 4th component is always omitted */
+ * NOTE: this is _exactly like matrix.col except the 4th component is always omitted. */
 
 uchar mathutils_matrix_translation_cb_index = -1;
 
@@ -1938,7 +1938,7 @@ static PyObject *Matrix_lerp(MatrixObject *self, PyObject *args)
     return NULL;
   }
 
-  /* TODO, different sized matrix */
+  /* TODO: different sized matrix. */
   if (self->num_col == 4 && self->num_row == 4) {
 #ifdef MATH_STANDALONE
     blend_m4_m4m4((float(*)[4])mat, (float(*)[4])self->matrix, (float(*)[4])mat2->matrix, fac);
@@ -3614,7 +3614,7 @@ static int MatrixAccess_ass_subscript(MatrixAccessObject *self, PyObject *item,
     }
     return Matrix_ass_item_col(matrix_user, i, value);
   }
-  /* TODO, slice */
+  /* TODO: slice. */
 
   PyErr_Format(
       PyExc_TypeError, "matrix indices must be integers, not %.200s", Py_TYPE(item)->tp_name);

source/blender/python/mathutils/mathutils_Quaternion.c

@@ -42,7 +42,7 @@ static PyObject *Quaternion_deepcopy(QuaternionObject *self, PyObject *args);
 
 /* -----------------------------METHODS------------------------------ */
 
-/* note: BaseMath_ReadCallback must be called beforehand */
+/* NOTE: BaseMath_ReadCallback must be called beforehand. */
 static PyObject *Quaternion_to_tuple_ext(QuaternionObject *self, int ndigits)
 {
   PyObject *ret;

source/blender/python/mathutils/mathutils_Vector.c

@@ -628,7 +628,7 @@ PyDoc_STRVAR(Vector_to_tuple_doc,
              "   :type precision: int\n"
              "   :return: the values of the vector rounded by *precision*\n"
              "   :rtype: tuple\n");
-/* note: BaseMath_ReadCallback must be called beforehand */
+/* NOTE: BaseMath_ReadCallback must be called beforehand. */
 static PyObject *Vector_to_tuple_ex(VectorObject *self, int ndigits)
 {
   PyObject *ret;
@@ -3019,8 +3019,7 @@ static struct PyMethodDef Vector_methods[] = {
 };
 
 /**
- * Note:
- * #Py_TPFLAGS_CHECKTYPES allows us to avoid casting all types to Vector when coercing
+ * NOTE: #Py_TPFLAGS_CHECKTYPES allows us to avoid casting all types to Vector when coercing
  * but this means for eg that (vec * mat) and (mat * vec)
  * both get sent to Vector_mul and it needs to sort out the order
  */

source/blender/python/mathutils/mathutils_bvhtree.c

@@ -1109,7 +1109,7 @@ PyDoc_STRVAR(C_BVHTree_FromObject_doc,
              "   :type cage: bool\n" PYBVH_FROM_GENERIC_EPSILON_DOC);
 static PyObject *C_BVHTree_FromObject(PyObject *UNUSED(cls), PyObject *args, PyObject *kwargs)
 {
-  /* note, options here match 'bpy_bmesh_from_object' */
+  /* NOTE: options here match #bpy_bmesh_from_object. */
   const char *keywords[] = {"object", "depsgraph", "deform", "cage", "epsilon", NULL};
 
   PyObject *py_ob, *py_depsgraph;

source/blender/python/mathutils/mathutils_geometry.c

@@ -1102,7 +1102,7 @@ static PyObject *M_Geometry_points_in_planes(PyObject *UNUSED(self), PyObject *a
     return NULL;
   }
 
-  /* note, this could be refactored into plain C easy - py bits are noted */
+  /* NOTE: this could be refactored into plain C easy - py bits are noted. */
 
   struct PointsInPlanes_UserData user_data = {
       .py_verts = PyList_New(0),