lang: Initial implementation of the mgmt language

This is an initial implementation of the mgmt language. It is a
declarative (immutable) functional, reactive, domain specific
programming language. It is intended to be a language that is:

* safe
* powerful
* easy to reason about

With these properties, we hope this language, and the mgmt engine will
allow you to model the real-time systems that you'd like to automate.

This also includes a number of other associated changes. Sorry for the
large size of this patch.

examples/lang/states0.mcl

@@ -0,0 +1,35 @@
+$ns = "estate"
+$exchanged = kvlookup($ns)
+
+$state = maplookup($exchanged, $hostname, "default")
+
+if $state == "one" || $state == "default" {
+
+	file "/tmp/mgmt/state" {
+		content => "state: one\n",
+	}
+	kv "${ns}" {
+		key => $ns,
+		value => "two",
+	}
+}
+if $state == "two" {
+
+	file "/tmp/mgmt/state" {
+		content => "state: two\n",
+	}
+	kv "${ns}" {
+		key => $ns,
+		value => "three",
+	}
+}
+if $state == "three" {
+
+	file "/tmp/mgmt/state" {
+		content => "state: three\n",
+	}
+	kv "${ns}" {
+		key => $ns,
+		value => "one",
+	}
+}