build: add an install target.

Makefile

+PREFIX=/usr
+BINDIR=$(PREFIX)/bin
+DATADIR=$(PREFIX)/share/espeak-data
+
 PLATFORM=big_endian
 
 .PHONY: all clean distclean espeak espeakedit espeak-phoneme-data espeak-data espeak-data-local
 
 all: espeak espeakedit espeak-data-local
 
+install:
+	cd src && make DESTDIR=$(DESTDIR) PREFIX=$(PREFIX) install && cd ..
+	install -m 755 src/espeakedit $(DESTDIR)$(BINDIR)
+	cp -prf espeak-data-local/* $(DESTDIR)$(DATADIR)
+
 clean:
 	cd src && rm -f *.o *~ && cd ..
 
 distclean: clean
 	cd src && rm -f libespeak.a libespeak.so.* speak espeak espeakedit && cd ..
-	cd platforms/${PLATFORM} && rm -f espeak-phoneme-data && cd ../..
+	cd platforms/$(PLATFORM) && rm -f espeak-phoneme-data && cd ../..
 	rm -rf espeak-data-local
 
 ##### build targets:
 
 espeak:
-	cd src && make && cd ..
+	cd src && make PREFIX=$(PREFIX) && cd ..
 
 espeakedit:
-	cd src && make -f Makefile.espeakedit && cd ..
+	cd src && make -f Makefile.espeakedit PREFIX=$(PREFIX) && cd ..
 
 espeak-phoneme-data:
-	cd platforms/${PLATFORM} && make && cd ../..
+	cd platforms/$(PLATFORM) && make PREFIX=$(PREFIX) && cd ../..
 
 espeak-data: espeakedit
-	cp -a espeak-data ${HOME}/espeak-data
-	cp -a phsource ${HOME}/espeak-data/phsource
-	cp -a dictsource ${HOME}/espeak-data/dictsource
+	cp -a espeak-data $(HOME)/espeak-data
+	cp -a phsource $(HOME)/espeak-data/phsource
+	cp -a dictsource $(HOME)/espeak-data/dictsource
 	src/espeakedit --compile
 
 espeak-data-local: espeak-phoneme-data espeak-data
-	cp -a ${HOME}/espeak-data espeak-data-local
-	platforms/${PLATFORM}/espeak-phoneme-data espeak-data-local espeak-data-local espeak-data-local/phondata-manifest
+	cp -a $(HOME)/espeak-data espeak-data-local
+	platforms/$(PLATFORM)/espeak-phoneme-data espeak-data-local espeak-data-local espeak-data-local/phondata-manifest