checkpoint milestone on manifest

All fields in both manifest.numbers and missing_manifest.numbers
have been filled in.  However the data entered needs to be reviewed.
Previous efforts made on a spreadsheet line by line basis.
What needs to happen next is to review at an entry by entry level.
Then a review at the overall manifest level (via full_manifest.numbers)
for overall consistency.

The 2015/burton/src.doc.rot13 was un-rot13ed to become
2015/burton/src.doc.txt.

Updated 2018/poikola and 2019/poikola .gitignore and make clobber
to address when the tex file is rendered.

2018/poikola/.gitignore

@@ -1,2 +1,6 @@
+poikola.aux
+poikola.log
+poikola.pdf
+poikola.synctex.gz
 prog
 prog.orig

2018/poikola/Makefile

@@ -209,6 +209,7 @@ clean:
 
 clobber: clean
 	${RM} -f ${TARGET} ${ALT_TARGET}
+	${RM} -f poikola.aux poikola.log poikola.pdf poikola.synctex.gz
 	@-if [ -e sandwich ]; then \
 	    ${RM} -f sandwich; \
 	    echo 'ate sandwich'; \