Examples can (and should) be exemplary C++

Obviously, the primary goal of the examples is to show how one uses the library.

However, they are also adding to the overall C++ knowledge: people using `thrust` are very likely to also learn the standard library algorithms, and take over the style presented (if not even copy-paste-adapt the examples).

So there would be value in making the example code exemplary, 'modern' C++.

Some instances of example code that could be modernized:

```
thrust::device_vector stencil(8);
stencil[0] = 0;
stencil[1] = 1;
...
```
could make use of `std::initializer_list` to direct initialize the vector.

```
std::cout << "found " << (indices_end - indices.begin()) ...
```
Should really use `std::distance(begin(indices), indices_end)`

```
// reduce a pair of bounding boxes (a,b) to a bounding box containing a and b
struct bbox_reduction : public thrust::binary_function
```
Is a poor choice of name: it tells you what function it's going to be used in (reduce), not what it does (bounding box of bounding boxes); it may be replaced by a lambda expression.

...

I think it would be a good idea to set up an 'example-wide' code review and try to exemplify that code.

(cf. also the very limited pull request NVIDIA/thrust#753)

Start by reviewing the existing Thrust examples and the referenced NVIDIA/thrust#753 pull request. Inventory modernization opportunities such as initialization, distance calculation, and callable naming; done means the examples consistently present modern, exemplary C++ without changing their teaching purpose.

Written by the indexing model from the issue text.