Dependency checks + important bugfix (#16)

scripts/dependencies_check

@@ -0,0 +1,30 @@
+# dependencies_check
+# $@	Dependnecy files to check
+#
+# Each dependency is in the form of a tool to test for, optionally followed by
+# a : and the name of a package if the package on a Debian-ish system is not
+# named for the tool (i.e., qemu-user-static).
+dependencies_check()
+{
+	local depfile deps missing
+
+	for depfile in "$@"; do
+		if [[ -e "$depfile" ]]; then
+			deps="$(sed -f "${SCRIPT_DIR}/remove-comments.sed" < ${BASE_DIR}/depends"
+
+		fi
+		for dep in $deps; do
+			if ! hash ${dep%:*} 2>/dev/null; then
+				missing="${missing:+$missing }${dep#*:}"
+			fi
+		done
+	done
+
+	if [[ "$missing" ]]; then
+		echo "Reqired dependencies not installed"
+		echo
+		echo "This can be resolved on Debian/Raspbian systems by installing:"
+		echo "$missing"
+		false
+	fi
+}