Work on standard libraries.

- Allows Standard Libraries to work with actual luatypes, to prevent constant back and forth casting
- adds ipairs function, doesn't do anything except maintain compatibility with lua
- several tests

UpsilonTests/StandardLibraryTests/BasicFunctionsTests.cs

@@ -25,5 +25,36 @@ namespace UpsilonTests.StandardLibraryTests
             Assert.Equal("test_error", e.Message);
         }
 
+        [Fact]
+        public void IPairsTest()
+        {
+            const string input = @"
+arr = {100, 56, 28}
+value = 0
+for key, val in ipairs(arr) do
+    value = value + val
+end
+return value
+";
+            var script = new Script(input, BoundScope, StaticScope);
+            Assert.Empty(script.Diagnostics.Messages);
+            var result = script.Evaluate<long>();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(184, result);
+        }
+
+        [Fact]
+        public void ToNumberTest()
+        {
+            const string input = @"
+return tonumber(""100"")
+";
+            var script = new Script(input, BoundScope, StaticScope);
+            Assert.Empty(script.Diagnostics.Messages);
+            var result = script.Evaluate<long>();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(100, result);
+        }
+
     }
 }