t/*: rearrange tests into numbered directories.

It was getting way too ad-hoc in there.  Let's reorganize the tests so that
there's a good, obvious, suggested sequence to run them in.

t/alwaystest.do

@@ -1,26 +0,0 @@
-rm -f always1 always1.log
-
-cd ..
-redo t/always1
-cd t
-[ "$(wc -l <always1.log)" -eq 1 ] || exit 11
-
-# This shouldn't rebuild, but because other people might be running
-# flush-cache in parallel with us, we can't be 100% sure it won't.  So don't
-# test it.
-#redo-ifchange always1
-#[ "$(wc -l <always1.log)" -eq 1 ] || exit 21
-
-./flush-cache
-redo-ifchange always1
-. ./skip-if-minimal-do.sh
-[ "$(wc -l <always1.log)" -eq 2 ] || exit 31
-
-./flush-cache
-redo-ifchange always1
-[ "$(wc -l <always1.log)" -eq 3 ] || exit 41
-
-cd ..
-./t/flush-cache
-redo-ifchange t/always1
-[ "$(wc -l <t/always1.log)" -eq 4 ] || exit 51