Drop "install" target and documentation.

This has hurt many many many people over it's lifetime, by confusing their
multilib toolchains.  Simply drop it outright.  People who _really_ know what
they're doing are still perfectly entitled to "install" portions of this
project in suitable locations for their own use.

Makefile

@@ -23,13 +23,6 @@ PREFIX		?= arm-none-eabi
 STYLECHECK      := scripts/checkpatch.pl
 STYLECHECKFLAGS := --no-tree -f --terse --mailback
 
-DESTDIR		?= /usr/local
-
-INCDIR		:= $(DESTDIR)/$(PREFIX)/include
-LIBDIR		:= $(DESTDIR)/$(PREFIX)/lib
-SHAREDIR	:= $(DESTDIR)/$(PREFIX)/share/libopencm3/scripts
-INSTALL		:= install
-
 space:=
 space+=
 SRCLIBDIR:= $(subst $(space),\$(space),$(realpath lib))
@@ -71,23 +64,6 @@ $(LIB_DIRS): $(IRQ_DEFN_FILES:=.genhdr)
 lib: $(LIB_DIRS)
 	$(Q)true
 
-install: lib
-	@printf "  INSTALL headers\n"
-	$(Q)$(INSTALL) -d $(INCDIR)/libopencm3
-	$(Q)$(INSTALL) -d $(INCDIR)/libopencmsis
-	$(Q)$(INSTALL) -d $(LIBDIR)
-	$(Q)$(INSTALL) -d $(SHAREDIR)
-	$(Q)cp -r include/libopencm3/* $(INCDIR)/libopencm3
-	$(Q)cp -r include/libopencmsis/* $(INCDIR)/libopencmsis
-	@printf "  INSTALL libs\n"
-	$(Q)$(INSTALL) -m 0644 lib/*.a $(LIBDIR)
-	@printf "  INSTALL ldscripts\n"
-	$(Q)$(INSTALL) -m 0644 lib/*.ld $(LIBDIR)
-	$(Q)$(INSTALL) -m 0644 lib/efm32/*/*.ld $(LIBDIR)
-	@printf "  INSTALL scripts\n"
-	$(Q)$(INSTALL) -m 0644 scripts/*.scr $(SHAREDIR)
-
-
 html doc:
 	$(Q)$(MAKE) -C doc html
 
@@ -130,4 +106,4 @@ genlinktests: $(LDTESTS:.data=.ldtest)
 	fi;
 
 
-.PHONY: build lib $(LIB_DIRS) install doc clean generatedheaders cleanheaders stylecheck genlinktests
+.PHONY: build lib $(LIB_DIRS) doc clean generatedheaders cleanheaders stylecheck genlinktests