Move to scons, add more infra

SConstruct

@@ -0,0 +1,63 @@
+from pathlib import Path
+
+#
+# File lists
+#
+
+build_dir = "build/default/"
+src_dir = "src/"
+
+program_sources = ["src/main.c"]
+lib_srcs = []
+lib_includes = ["src/"]
+
+test_srcs = [""]
+test_lib_srcs = ["third-party/unity/src/unity.c"]
+test_lib_includes = ["third-party/unity/src/"]
+
+#
+# Construct Environments
+#
+
+VariantDir(build_dir, ".", duplicate=0)
+env = Environment(CPPPATH=lib_includes, COMPILATIONDB_USE_ABSPATH=True)
+env.Tool('compilation_db')
+env.CompilationDatabase()
+
+test_env = env.Clone()
+test_env.Append(CPPPATH=test_lib_includes)
+
+#
+# Construct Environments
+#
+
+# Generate REPL
+
+
+lib_objs = [env.Object(p) for p in lib_srcs]
+env.Program(build_dir + "nihilispm", lib_objs + program_sources)
+
+# Generate unit test executables
+
+test_lib_objs = [
+    test_env.Object(build_dir + p, CPPPATH=lib_includes + test_lib_includes) for p in test_lib_srcs
+]
+test_deps = test_lib_objs + lib_objs
+tests = [test_env.Program(build_dir + p, [p] + test_deps) for p in test_srcs]
+
+#
+# Generate Test Runner script
+#
+
+env.Substfile(
+    "run_tests.sh.in",
+    SUBST_DICT={
+        "@tests@": " ".join(str(Path(str(test[0])).resolve()) for test in tests)
+    },
+)
+
+env.Command(build_dir + "run_tests", "run_tests.sh", Chmod("run_tests.sh", 0o755))
+
+# Copy default build compile commands to root, which is where tools seem to want
+# it.
+Copy("compile_commands.json", build_dir + "compile_commands.json")