Moved the stripping of date comments (strip_tags) to its own target

"html-dist", just like it has been done for pdf-dist.

Stripping the date comments roughly doubled the time of html generation
for daily use, although it is only needed before a web update.

*** Please use "make html-dist" before updating the web docs. ***

Just for reference: Measurement values on my Windows system with cygwin:
 - make html	1:01 minutes
 - strip_tags	1:05 minutes
 - strip_tags	0:49 minutes after removal of cat

Todo:
 - Why do we need the external script strip_tags, are there reasons not to
   integrate it in the Makefile?
 - If it would be in the Makefile, should we use ${RM} instead of literally
   using "rm" ?


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6702 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

documentation/Makefile

@@ -271,6 +271,8 @@ html/index.html: $(HTMLFILES) $(IMAGEFILES) Doxyfile
 	-$(RMDIR) html
 	-$(INSTALL_DIR) html
 	-$(DOXYDOC)
+
+html-dist: html
 	echo "Stripping HTML files..."
 	./strip_tags
 
@@ -279,7 +281,7 @@ html/index.html: $(HTMLFILES) $(IMAGEFILES) Doxyfile
 #	$(RM) fltk.ps
 #	-$(HTMLDOC) --verbose --batch $(SRC_DOCDIR)/fltk.book $(MEDIA) -f fltk.ps
 
-pdf-dist : latex/refman.pdf
+pdf-dist: latex/refman.pdf
 	cp -f latex/refman.pdf fltk.pdf
 
 pdf: 	latex/refman.pdf

documentation/strip_tags

@@ -1,5 +1,5 @@
 for f in html/*.html ; do
-  cat $f | sed 's/<!-- ... ... .*:..:.. ....\. -->/<!-- date removed for reducing unnecessary svn web updates  -->/' > $f.tmp
+  sed 's/<!-- ... ... .*:..:.. ....\. -->/<!-- date removed for reducing unnecessary svn web updates  -->/' $f > $f.tmp
   rm $f
   mv $f.tmp $f
 done