Improve 2015/howe/try.sh and fix make clobber

The make clobber rule now removes *.tmp instead of just specific .tmp
files.

Updated .gitignore: removed the foo.tmp globs and added *.tmp.

2015/howe/.gitignore

@@ -1,31 +1,12 @@
 #
 # sort with: sort -d -u
-123.tmp
-1.tmp
-ABCABBA.tmp
-ABCDEFGHIJK.tmp
-ABCDEF.tmp
-ABCDE.tmp
-ABCD.tmp
-ABCEFGIJKDEFGHIJK.tmp
-ABD.tmp
-ABXYEFCD.tmp
-ACBDEACBED.tmp
-ACDBECFD.tmp
-ACEBDABBABED.tmp
-A.tmp
-CBABAC.tmp
-EMPTY.tmp
-curds.tmp
 *.dSYM
 indent
 indent.c
 indent.o
 makeholes
-nuked.tmp
-patch.tmp
 prog
 prog.alt
 prog.orig
+*.tmp
 war-and-peace.txt
-whey.tmp