Improve structure of Makefiles

Makefile

@@ -13,9 +13,9 @@ libdir:
         
 
 mlp:
-	cd mlprec && $(MAKE) all
+	$(MAKE) -C mlprec all
 cbnd: mlp
-	cd cbind && $(MAKE) all
+	$(MAKE) -C cbind all
 install: all
 	mkdir -p $(INSTALL_LIBDIR) &&\
 	   $(INSTALL_DATA) lib/*.a  $(INSTALL_LIBDIR)

cbind/Makefile

@@ -15,11 +15,11 @@ lib: mlprecd
 
 
 mlprecd:
-	cd mlprec && $(MAKE) lib LIBNAME=$(LIBNAME) 
+	$(MAKE) -C mlprec lib LIBNAME=$(LIBNAME) 
 
 
 clean: 
-	cd mlprec && $(MAKE) clean
+	$(MAKE) -C mlprec clean
 
 
 veryclean: clean

mlprec/Makefile

@@ -55,7 +55,7 @@ LIBNAME=libmld_prec.a
 all: lib impld
 
 impld: $(OBJS)
-	cd impl && $(MAKE)
+	$(MAKE) -C impl
 
 lib: $(OBJS) impld
 	$(AR) $(HERE)/$(LIBNAME) $(OBJS)
@@ -172,4 +172,4 @@ clean: implclean
 	/bin/rm -f $(OBJS) $(LOCAL_MODS) *$(.mod)
 
 implclean:
-	cd impl && $(MAKE) clean
+	$(MAKE) -C impl clean

mlprec/impl/Makefile

@@ -72,13 +72,13 @@ lib:  $(OBJS) aggrd levd smoothd solvd
 	$(RANLIB) $(HERE)/$(LIBNAME)
 
 aggrd:
-	cd aggregator && $(MAKE)
+	$(MAKE) -C aggregator
 levd:
-	cd level && $(MAKE)
+	$(MAKE) -C level
 smoothd:
-	cd smoother && $(MAKE)
+	$(MAKE) -C smoother
 solvd:
-	cd solver && $(MAKE)
+	$(MAKE) -C solver
 
 mpobjs: 
 	(make $(MPFOBJS) FC="$(MPFC)" FCOPT="$(FCOPT)")
@@ -91,10 +91,10 @@ clean: solvclean smoothclean levclean aggrclean
 	/bin/rm -f $(OBJS) $(LOCAL_MODS)
 
 aggrclean:
-		cd aggregator && $(MAKE) clean
+		$(MAKE) -C aggregator clean
 levclean:
-		cd level && $(MAKE) clean
+		$(MAKE) -C level clean
 smoothclean:
-		cd smoother && $(MAKE) clean
+		$(MAKE) -C smoother clean
 solvclean:
-		cd solver && $(MAKE) clean
+		$(MAKE) -C solver clean