Change runtime library to non-DLL version to match LibOVR

Because LibOVR is not included in the repository, we cannot alter the
library's project configuration.  We could add an instruction in README
to modify the configuration by the user, but it bothers to do such a
task prior to compiling.
Add libpng project for static library and a solution file

Libpng only supplies DLL version of the project, but it bothers to place
the DLL in an appropriate path when debugging, so we prefer static library
linked to OculusBilliard.  Statically linking also will help easy
installation.