Rocks'n'Diamonds browser runtime packaged for PLAYCHIVE

Upstream source: https://git.artsoft.org/rocksndiamonds.git
Pinned revision: b42509b0cc55e6eb6b48953be946c09ac24cf6a3
Upstream project: https://www.artsoft.org/rocksndiamonds/

Rocks'n'Diamonds is distributed under the GNU GPL version 2 or later. The
full license is retained at ROCKSNDIAMONDS-GPL-2.0-OR-LATER.txt. Complete
corresponding source is available from the upstream Git repository above; the
PLAYCHIVE packaging script is scripts/build-rocksndiamonds-web.sh.

Packaging changes: a compile guard encloses a Windows-only SDL DPI hint that is
not present in SDL's Emscripten build. The runtime packages the project's
included configuration, documentation, levels, graphics, sounds and music as
local Emscripten data. It does not fetch playable content, require an upload,
or contact a network game server.