Handle large numbers of source files better

Don't print all the possible 'make foo.pdf' commands when there are so
many source files (not all of which are necessarily even buildable on
their own) that the list would be very long.

Makefile

@@ -11,14 +11,35 @@ endif
 default: help
 
 help:
-	@echo 'You can build PDF for any document here by running "make DOCUMENT.pdf".'
-	@echo 'If you put ".draft" before the file extension, you get a version with a'
+	@echo 'Build a specific PDF here by running "make DOCUMENT_NAME.pdf".'
+	@echo 'If you put ".draft" before the file extension, you get a version with'
 	@echo 'a "DRAFT" watermark diagonally across the background of each page.'
-	@echo 'You can build all non-draft PDFs with "make all".'
-	@echo ''
-	@for name in *.ltx; do echo "  make `basename $${name} .ltx`.pdf"; done
-	@for name in *.ltx; do echo "  make `basename $${name} .ltx`.draft.pdf"; done
+	@echo 'You may be able to build all non-draft PDFs with "make all".'
+	@if [ `ls -1 *.ltx | wc -l` -lt 5 ]; then              \
+	  echo "";                                             \
+	  for name in *.ltx; do                                \
+            echo "  make `basename $${name} .ltx`.pdf";        \
+	  done;                                                \
+	  echo "";                                             \
+	  for name in *.ltx; do                                \
+	    echo "  make `basename $${name} .ltx`.draft.pdf";  \
+	  done;                                                \
+        fi	
 
+# The 'make all' and 'make all-drafts' functionality only works in
+# directories where each .ltx file corresponds to an output .pdf.
+# When there's a main .ltx file that includes lots of subsidiary
+# .ltx files (which are also present in the dir), then making 'all'
+# doesn't work because we don't know which doc is the real target.
+#
+# There are various possible solutions to this.  One is to autodetect
+# the primary .ltx files, for example by looking for certain headers
+# or by counting the number of times "\input" or "\include" appears.
+# Another way would be to have a control file ('.ots-doctools-cfg'
+# or something) that names the primary documents.
+#
+# But for now, we just punt on the whole issue.  In the 'help' rule
+# instructions above, we weasel out by saying "You may be able to..."
 all:
 	@for name in *.ltx; do $(MAKE) `basename $${name} .ltx`.pdf; done
 

ext-Makefile

@@ -12,11 +12,11 @@
 ### ${OTS_DOCTOOLS_DIR}/Makefile.  Therefore, please try not to make
 ### changes here; instead, put any improvements in the other Makefile.
 
-.PHONY: all check
+.PHONY: default check
 
 # The order of the rules below is important; change only with care.
 
-all: check
+default: check
 	@make -s -f ${OTS_DOCTOOLS_DIR}/Makefile
 
 %: check