Replace C-style casts

[DanRStevens]

Reference: #528 (-Wold-style-cast)

Replaces old C-style casts with static_cast or reinterpret_cast.

[cugone]

The Core Guidelines suggest avoiding casts unless absolutely necessary.

We should consider all uses of casting to see if there can be a better solution such as T{e} construction, functions, safe wide-conversions (passing in a float to a double argument, etc), among other things.

[DanRStevens]

Agreed. At least using the newer X_cast syntax allows you to search for casts, so they can be found and fixed easier.

[cugone]

In particular, any non-pointer reinterpret_cast is suspect.