samples: add Terra samples

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

samples/Terra/selectoverload.t

@@ -0,0 +1,25 @@
+struct Vec { data : float[3] }
+
+
+local get = {}
+get.x = terra(self : &Vec)
+    return self.data[0]
+end
+get.y = macro(function(self)
+    return `self.data[1]
+end)
+    
+Vec.metamethods.__entrymissing = macro(function(name,self)
+    return `[get[name]](&self) 
+end)
+
+terra bar()
+    var a = Vec { array(1.f,2.f,3.f) }
+    a.y = a.y + 1
+    var pa = &a
+    return a.x + a.y + pa.x
+end
+
+local test = require("test")
+test.eq(bar(),5)
+