Vendor the Shockolate engine and build it via a Docker image with every

dependency (SDL2, SDL2_mixer, fluidsynth-lite, a MIDI soundfont)
prebuilt, so compiling the engine needs no network access - just the
image and the engine source. Add res/assets/extract_assets.sh to pull
the game's data files out of a purchased GOG installer, and a Makefile
that assembles a runnable dist/ from the two.

Also add `make package`, which builds a redistributable tarball that
omits the proprietary game assets (shipping res/GET_ASSETS.txt instead)
plus license information for both the MIT tooling and the GPLv3 engine,
and a Gitea Actions workflow that builds and publishes it to
dl.ladkau.de on every push.

engine/src/GameSrc/Headers/cybmem.h

@@ -0,0 +1,64 @@
+/*
+
+Copyright (C) 2015-2018 Night Dive Studios, LLC.
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+#ifndef __CYBMEM_H
+#define __CYBMEM_H
+
+/*
+ * $Source: r:/prj/cit/src/inc/RCS/cybmem.h $
+ * $Revision: 1.23 $
+ * $Author: xemu $
+ * $Date: 1994/11/01 09:19:29 $
+ *
+ */
+
+// Defines
+
+// Typedefs
+
+// Prototypes
+errtype load_dynamic_memory(int mask);
+errtype free_dynamic_memory(int mask);
+int avail_memory(int debug_src);
+void Memory_Check();
+int slorkatron_memory_check();
+int flush_resource_cache(void);
+
+// If LZW stuff ever gets lots more efficient, may need to raise this up some.
+#define BIG_BUFFER_SIZE (LZW_BUFF_SIZE + 3)
+
+#define MINIMUM_GAME_THRESHOLD 540000 // this will be tweaked as appropriate...
+#define BIG_CACHE_THRESHOLD MINIMUM_GAME_THRESHOLD + 1900000
+
+#define EXTRA_TMAP_THRESHOLD BIG_CACHE_THRESHOLD
+
+#define BLEND_THRESHOLD EXTRA_TMAP_THRESHOLD + 64000
+#define BIG_HACKCAM_THRESHOLD BLEND_THRESHOLD + 32000
+
+#define PRELOAD_ANIMATION_THRESHOLD EXTRA_TMAP_THRESHOLD // for simplicity, can be set different if we are psyched
+
+// Globals
+#ifdef __CYBMEM_SRC
+uchar big_buffer[BIG_BUFFER_SIZE + 16384];
+int start_mem;
+#else
+extern uchar big_buffer[BIG_BUFFER_SIZE + 16384];
+extern int start_mem;
+#endif
+
+#endif // __CYBMEM_H