samples: add Terra samples

source: https://github.com/zdevito/terra/tree/master/tests

samples/Terra/veclit.t

@@ -0,0 +1,29 @@
+
+terra foo()
+	var a = 2* vector(1,2,3)
+	return a[0] + a[1] + a[2]
+end
+
+terra foo2()
+	var a = vector(1,2.5,3)
+	return a[1]
+end
+terra what()
+	return 3,4.5
+end
+expwhat = macro(function(a) return {`a._0, `a._1} end)
+terra foo3()
+	var a = vector(1,2.5,expwhat(what()))
+	return a[3]
+end
+
+terra foo4()
+	var a = vectorof(int,1,2.5,3)
+	return a[1]
+end
+
+local test = require("test")
+test.eq(foo(),12)
+test.eq(foo2(),2.5)
+test.eq(foo3(),4.5)
+test.eq(foo4(),2)