Various unit test cleanup.

Updated README and collected coverage-related tests in a common dir.

There are still coverage failures resulting from either the following
scripts not being @load'd in the default bro mode:

base/frameworks/time-machine/notice.bro
base/protocols/http/partial-content.bro
base/protocols/rpc/main.bro

Or the following result in errors when @load'd:

policy/protocols/conn/scan.bro
policy/hot.conn.bro

If these are all scripts-in-progress, can we move them all to live
outside the main scripts/ directory until they're ready?

testing/btest/scripts/bare-mode-coverage.test

@@ -1,8 +0,0 @@
-# Makes sure any given policy script in the scripts/ tree can be loaded in
-# bare mode.  btest-bg-run/btest-bg-wait are used to kill off scripts that
-# block after loading, e.g. start listening on a socket.
-#
-# @TEST-EXEC: test -d $DIST/scripts
-# @TEST-EXEC: for script in `find $DIST/scripts -name \*\.bro`; do echo $script;if [[ "$script" =~ listen-clear|listen-ssl|controllee ]]; then rm -rf load_attempt .bgprocs; btest-bg-run load_attempt bro -b $script; btest-bg-wait -k 2; cat load_attempt/.stderr >>allerrors; else bro -b $script 2>>allerrors; fi done || exit 0
-# @TEST-EXEC: cat allerrors | grep -v "received termination signal" | sort | uniq > unique_errors
-# @TEST-EXEC: btest-diff unique_errors

testing/btest/scripts/base/init-default-coverage.bro

@@ -1,11 +0,0 @@
-# Makes sure that all base/* scripts are loaded by default via init-default.bro;
-# and that all scripts loaded there in there actually exist.
-
-#@TEST-EXEC: test -d $DIST/scripts/base
-#@TEST-EXEC: test -e $DIST/scripts/base/init-default.bro
-#@TEST-EXEC: ( cd $DIST/scripts/base && find . -name '*.bro' ) | sort >"all scripts found"
-#@TEST-EXEC: bro misc/loaded-scripts
-#@TEST-EXEC: cat loaded_scripts.log | egrep -v '/build/|/loaded-scripts.bro|#' | awk 'NR>1{print $2}' | sed 's#/./#/#g'  >loaded_scripts.log.tmp
-#@TEST-EXEC: cat loaded_scripts.log.tmp | sed -e ':a' -e '$!N' -e 's/^\(.*\).*\n\1.*/\1/' -e 'ta' >prefix
-#@TEST-EXEC: cat loaded_scripts.log.tmp | sed "s#`cat prefix`#./#g" | sort >init-default.bro
-#@TEST-EXEC: diff -u "all scripts found" init-default.bro 1>&2

testing/btest/scripts/policy/misc/bare-loaded-scripts.test

@@ -1,12 +0,0 @@
-# This test is meant to cover whether the set of scripts that get loaded by
-# default in bare mode matches a baseline of known defaults.
-#
-# As the output has absolute paths in it, we need to remove the common
-# prefix to make the test work everywhere. That's what the sed magic
-# below does. Don't ask. :-)
-
-# @TEST-EXEC: bro -b misc/loaded-scripts
-# @TEST-EXEC: test -e loaded_scripts.log
-# @TEST-EXEC: cat loaded_scripts.log | egrep -v '#' | awk 'NR>1{print $2}' | sed -e ':a' -e '$!N' -e 's/^\(.*\).*\n\1.*/\1/' -e 'ta' >prefix
-# @TEST-EXEC: cat loaded_scripts.log | sed "s#`cat prefix`##g" >canonified_loaded_scripts.log
-# @TEST-EXEC: btest-diff canonified_loaded_scripts.log

testing/btest/scripts/policy/misc/default-loaded-scripts.test

@@ -1,12 +0,0 @@
-# This test is meant to cover whether the set of scripts that get loaded by
-# default matches a baseline of known defaults.
-#
-# As the output has absolute paths in it, we need to remove the common
-# prefix to make the test work everywhere. That's what the sed magic
-# below does. Don't ask. :-)
-
-# @TEST-EXEC: bro misc/loaded-scripts
-# @TEST-EXEC: test -e loaded_scripts.log
-# @TEST-EXEC: cat loaded_scripts.log | egrep -v '#' | awk 'NR>1{print $2}' | sed -e ':a' -e '$!N' -e 's/^\(.*\).*\n\1.*/\1/' -e 'ta' >prefix
-# @TEST-EXEC: cat loaded_scripts.log | sed "s#`cat prefix`##g" >canonified_loaded_scripts.log
-# @TEST-EXEC: btest-diff canonified_loaded_scripts.log

testing/btest/scripts/test-all-policy-coverage.bro

@@ -1,8 +0,0 @@
-# Makes sure that all policy/* scripts are loaded in test-all-policy.bro; and that
-# all scripts loaded there actually exist.
-
-@TEST-EXEC: test -e $DIST/scripts/test-all-policy.bro
-@TEST-EXEC: test -d $DIST/scripts
-@TEST-EXEC: ( cd $DIST/scripts/policy && find . -name '*.bro' ) | sort >"all scripts found"
-@TEST-EXEC: cat $DIST/scripts/test-all-policy.bro | grep '@load' | sed 'sm^\( *# *\)\{0,\}@load *m./mg' | sort >test-all-policy.bro
-@TEST-EXEC: diff -u "all scripts found" test-all-policy.bro 1>&2