Reorganize makefile and scripts.

Makefile

@@ -1,18 +1,53 @@
+# Compiler flags.
+CFLAGS = -std=c99 -Wall -Werror
+# TODO: Add -Wextra.
+DEBUG_CFLAGS = -O0 -DDEBUG
+RELEASE_CFLAGS = -Os
+
+# Files.
+SOURCES = $(wildcard src/*.c)
+HEADERS = $(wildcard src/*.h)
+OBJECTS = $(SOURCES:.c=.o)
+
+DEBUG_OBJECTS = $(addprefix build/debug/, $(notdir $(OBJECTS)))
+RELEASE_OBJECTS = $(addprefix build/release/, $(notdir $(OBJECTS)))
+
 .PHONY: all clean test docs corelib
 
-all:
-	gcc -Iinclude src/*.c -owren
-	mkdir -p build/Release
-	mv wren build/Release
+all: release
+
+# Debug build.
+debug: prep wrend
+
+wrend: $(DEBUG_OBJECTS)
+	$(CC) $(CFLAGS) $(DEBUG_CFLAGS) -Iinclude -o wrend $^
+
+build/debug/%.o: src/%.c include/wren.h $(HEADERS)
+	$(CC) -c $(CFLAGS) $(DEBUG_CFLAGS) -Iinclude -o $@ $<
+
+# Release build.
+release: prep wren
+
+wren: $(RELEASE_OBJECTS)
+	$(CC) $(CFLAGS) $(RELEASE_CFLAGS) -Iinclude -o wren $^
+
+build/release/%.o: src/%.c include/wren.h $(HEADERS)
+	$(CC) -c $(CFLAGS) $(RELEASE_CFLAGS) -Iinclude -o $@ $<
 
 clean:
-	rm -rf build
+	rm -rf build wren wrend
 
-test:
-	@./runtests
+prep:
+	mkdir -p build/debug build/release
 
+# Run the tests against the debug build of Wren.
+test: wrend
+	@./script/test.py
+
+# Generate the Wren site.
 docs:
-	@./make_docs
+	@./script/generate_docs.py --watch
 
+# Take the contents of corelib.wren and copy them into src/wren_core.c.
 corelib:
-	@./make_corelib
+	@./script/generate_corelib.py