message: Replace `DEPDIR` with `OBJDIR`
  We only really need one variable to represent a generic intermediate
  folder. Simplify.
diff: @@ -4,7 +4,6 @@ SRCDIR := src
  BUILDDIR := .build
  BINDIR := .
  OBJDIR := $(BUILDDIR)/obj
  -DEPDIR := $(BUILDDIR)/deps
  EXE := $(BINDIR)/OPHD
  NAS2DDIR := nas2d-core
  NAS2DINCLUDEDIR := $(NAS2DDIR)/include
  @@ -16,10 +15,10 @@ LDFLAGS := -lstdc++ -lm -L$(NAS2DLIBDIR) -lnas2d \
  $(shell sdl2-config --libs) -lSDL2 -lSDL2_image -lSDL2_mixer -lSDL2_ttf \
  -lphysfs -lGL -lGLEW
  -DEPFLAGS = -MT $@ -MMD -MP -MF $(DEPDIR)/$*.Td
  +DEPFLAGS = -MT $@ -MMD -MP -MF $(OBJDIR)/$*.Td
  COMPILE.cpp = $(CXX) $(DEPFLAGS) $(CFLAGS) $(TARGET_ARCH) -c
  -POSTCOMPILE = @mv -f $(DEPDIR)/$*.Td $(DEPDIR)/$*.d && touch $@
  +POSTCOMPILE = @mv -f $(OBJDIR)/$*.Td $(OBJDIR)/$*.d && touch $@
  SRCS := $(shell find $(SRCDIR) -name '*.cpp')
  OBJS := $(patsubst $(SRCDIR)/%.cpp,$(OBJDIR)/%.o,$(SRCS))
  @@ -38,19 +37,19 @@ $(NAS2DLIB): nas2d
  nas2d:
  $(MAKE) -C nas2d-core
  -$(OBJS): $(OBJDIR)/%.o : $(SRCDIR)/%.cpp $(DEPDIR)/%.d | build-folder
  +$(OBJS): $(OBJDIR)/%.o : $(SRCDIR)/%.cpp $(OBJDIR)/%.d | build-folder
  $(COMPILE.cpp) $(OUTPUT_OPTION) $<
  $(POSTCOMPILE)
  .PHONY: build-folder
  build-folder:
  @mkdir -p $(patsubst $(SRCDIR)/%,$(OBJDIR)/%, $(FOLDERS))
  - @mkdir -p $(patsubst $(SRCDIR)/%,$(DEPDIR)/%, $(FOLDERS))
  + @mkdir -p $(patsubst $(SRCDIR)/%,$(OBJDIR)/%, $(FOLDERS))
  -$(DEPDIR)/%.d: ;
  -.PRECIOUS: $(DEPDIR)/%.d
  +$(OBJDIR)/%.d: ;
  +.PRECIOUS: $(OBJDIR)/%.d
  -include $(wildcard $(patsubst $(SRCDIR)/%.cpp,$(DEPDIR)/%.d,$(SRCS)))
  +include $(wildcard $(patsubst $(SRCDIR)/%.cpp,$(OBJDIR)/%.d,$(SRCS)))
  .PHONY: clean clean-all
  clean:
  