Simplify and clean up Makefile

Don't explicitly specify permissions, since they're already the defaults.
Use `-D` flag to create missing directories instead of creating beforehand.
Force remove in uninstall instead of testing existence to avoid race condition.
Remove unnecessary Make variable.
Quote paths for safety in case of whitespace.

Author: Leo Pham

Makefile

@@ -2,16 +2,13 @@ ifeq ($(PREFIX),)
 	PREFIX := /usr/local
 endif
 
-pkgdatadir = $(PREFIX)/share/mantabassets
 .PHONY: install
 install:
-	sed "s|@pkgdatadir[@]|$(pkgdatadir)|g" mantablockscreen.in > mantablockscreen
-	install -d $(DESTDIR)$(PREFIX)/bin
-	install -d $(DESTDIR)$(PREFIX)/share/mantabassets
-	install -m 755 mantablockscreen $(DESTDIR)$(PREFIX)/bin/mantablockscreen
-	install -m 755 mantabassets/* $(DESTDIR)$(PREFIX)/share/mantabassets/
+	sed 's|@pkgdatadir[@]|$(PREFIX)/share/mantabassets|g' mantablockscreen.in > mantablockscreen
+	install -D mantablockscreen '$(DESTDIR)$(PREFIX)/bin/mantablockscreen'
+	install -D mantabassets/* -t '$(DESTDIR)$(PREFIX)/share/mantabassets/'
 
 .PHONY: uninstall
 uninstall:
-	test -e $(DESTDIR)$(PREFIX)/bin/mantablockscreen && rm $(DESTDIR)$(PREFIX)/bin/mantablockscreen
-	test -d $(DESTDIR)$(PREFIX)/share/mantabassets && rm -rf $(DESTDIR)$(PREFIX)/share/mantabassets || exit 0
+	rm -f '$(DESTDIR)$(PREFIX)/bin/mantablockscreen'
+	rm -rf '$(DESTDIR)$(PREFIX)/share/mantabassets'