message: Cleanup makefile variables for NAS2D
diff: # Source http://make.mad-scientist.net/papers/advanced-auto-dependency-generation/
  SRCDIR := src
  -INCDIR := nas2d-core/include
  -LIBDIR := nas2d-core/lib
  BUILDDIR := build
  BINDIR := .
  OBJDIR := $(BUILDDIR)/obj
  DEPDIR := $(BUILDDIR)/deps
  EXE := $(BINDIR)/OPHD
  -NAS2DLIB := $(LIBDIR)/libnas2d.a
  +NAS2DDIR := nas2d-core
  +NAS2DINCLUDEDIR := $(NAS2DDIR)/include
  +NAS2DLIBDIR := $(NAS2DDIR)/lib
  +NAS2DLIB := $(NAS2DLIBDIR)/libnas2d.a
  -CFLAGS := -std=c++11 -g -Wall -Wno-unknown-pragmas -I$(INCDIR) $(shell sdl2-config --cflags)
  -LDFLAGS := -lstdc++ -lm -L$(LIBDIR) -lnas2d \
  +CFLAGS := -std=c++11 -g -Wall -Wno-unknown-pragmas -I$(NAS2DINCLUDEDIR) $(shell sdl2-config --cflags)
  +LDFLAGS := -lstdc++ -lm -L$(NAS2DLIBDIR) -lnas2d \
  $(shell sdl2-config --libs) -lSDL2 -lSDL2_image -lSDL2_mixer -lSDL2_ttf \
  -lphysfs -lGLU -lGL -lGLEW
  