Added unit tests for namespaces.

These demonstrate the global scope of namespaces, defining functions and variables within namespaces, and namespace nesting by copy or reference.

unittests/namespaces.chai

@@ -0,0 +1,7 @@
+namespace("math")
+
+math.square = fun(x) { x * x }
+math.sum_squares = fun(x, y) { math.square(x) + math.square(y) }
+
+assert_equal(16, math.square(4))
+assert_equal(29, math.sum_squares(2, 5))

unittests/namespaces_nested_copy.chai

@@ -0,0 +1,9 @@
+namespace("parent")
+namespace("child")
+
+child.x = 3.0
+parent.child = child
+parent.child.x = 5.0
+
+assert_equal(3.0, child.x)
+assert_equal(5.0, parent.child.x)

unittests/namespaces_nested_ref.chai

@@ -0,0 +1,9 @@
+namespace("parent")
+namespace("child")
+
+child.x = 3.0
+parent.child := child
+parent.child.x = 5.0
+
+assert_equal(5.0, child.x)
+assert_equal(5.0, parent.child.x)