scalar: allow building and installing the documentation

Now that Scalar is reasonably complete, we are comfortable having users
install its documentation, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

contrib/scalar/.gitignore

@@ -1,2 +1,5 @@
+/*.xml
+/*.1
+/*.html
 /*.exe
 /scalar

contrib/scalar/Makefile

@@ -21,6 +21,7 @@ $(TARGETS): $(GITLIBS) scalar.c
 
 clean:
 	$(RM) $(TARGETS) ../../bin-wrappers/scalar
+	$(RM) scalar.1 scalar.html scalar.xml
 
 ../../bin-wrappers/scalar: ../../wrap-for-bin.sh Makefile
 	@mkdir -p ../../bin-wrappers
@@ -35,11 +36,34 @@ test: all
 INSTALL = install
 prefix = $(HOME)
 bindir = $(prefix)/bin
+mandir ?= $(prefix)/share/man
+man1dir = $(mandir)/man1
+htmldir ?= $(prefix)/share/doc/git-doc
 DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
 bindir_SQ = $(subst ','\'',$(bindir))
+man1dir_SQ = $(subst ','\'',$(man1dir))
+htmldir_SQ = $(subst ','\'',$(htmldir))
 
 install:
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(bindir_SQ)'
 	$(INSTALL) scalar$(X) '$(DESTDIR_SQ)$(bindir_SQ)'
 
-.PHONY: $(GITLIBS) all clean test install FORCE
+docs: scalar.html scalar.1
+
+scalar.html: | scalar.1 # prevent them from trying to build `doc.dep` in parallel
+
+scalar.html scalar.1: scalar.txt
+	$(QUIET_SUBDIR0)../../Documentation$(QUIET_SUBDIR1) \
+		MAN_TXT=../contrib/scalar/scalar.txt \
+		../contrib/scalar/$@
+	$(QUIET)test scalar.1 != "$@" || mv ../../Documentation/$@ .
+
+install-doc: scalar.1
+	$(INSTALL) -d -m 755 $(DESTDIR_SQ)$(man1dir_SQ)
+	$(INSTALL) -m 644 $^ $(DESTDIR_SQ)$(man1dir_SQ)
+
+install-html: scalar.html
+	$(INSTALL) -d -m 755 $(DESTDIR_SQ)$(htmldir_SQ)
+	$(INSTALL) -m 644 $^ $(DESTDIR_SQ)$(htmldir_SQ)
+
+.PHONY: $(GITLIBS) all clean test docs install install-doc install-html FORCE