Major restructuring to switch build system from old scripts to GNU Automake.

tests/Modifiers_-_--interval.test

@@ -0,0 +1,21 @@
+#!/bin/sh
+#
+# Check that the update interval can be set.
+
+# Dummy assignments for "shellcheck".
+testSubject="${testSubject:-false}"; workFile1="${workFile1:-.tmp1}"
+
+sleep 1 | "${testSubject}" -f -i 0.1 >/dev/null 2>"${workFile1}"
+
+# There should be more than 6 lines of output.
+#
+lineCount=$(tr '\r' '\n' < "${workFile1}" | wc -l | tr -dc '0-9')
+if ! test "${lineCount}" -gt 6; then
+	echo "fewer than 7 lines of output"
+	tr '\r' '\n' < "${workFile1}"
+	exit 1
+fi
+
+exit 0
+
+# EOF