VM and compiler update (#63)

* renamed test folders and fixed bug where wrong jump labels would be exectuted for rewrite.

* Added support for Osize (len(string)) and factored out the array tests

* Added current instruction number to VM prompt if program is loaded.

* added support for unary expressions.

* updated README of and sorted the help commands

* updated readme of the compiler

* bumped version -> 0.39.0

pkg/vm/tests/binary_expr_test.go

@@ -0,0 +1,116 @@
+package vm_test
+
+import "math/big"
+
+var binaryExprTestCases = []testCase{
+	{
+		"simple add",
+		`
+		package testcase
+		func Main() int {
+			x := 2 + 2
+			return x
+		}
+		`,
+		big.NewInt(4),
+	},
+	{
+		"simple sub",
+		`
+		package testcase
+		func Main() int {
+			x := 2 - 2
+			return x
+		}
+		`,
+		big.NewInt(0),
+	},
+	{
+		"simple div",
+		`
+		package testcase
+		func Main() int {
+			x := 2 / 2
+			return x
+		}
+		`,
+		big.NewInt(1),
+	},
+	{
+		"simple mul",
+		`
+		package testcase
+		func Main() int {
+			x := 4 * 2
+			return x
+		}
+		`,
+		big.NewInt(8),
+	},
+	{
+		"simple binary expr in return",
+		`
+		package testcase
+		func Main() int {
+			x := 2
+			return 2 + x
+		}
+		`,
+		big.NewInt(4),
+	},
+	{
+		"complex binary expr",
+		`
+		package testcase
+		func Main() int {
+			x := 4
+			y := 8
+			z := x + 2 + 2 - 8
+			return y * z
+		}
+		`,
+		big.NewInt(0),
+	},
+	{
+		"compare equal strings",
+		`
+		package testcase
+		func Main() int {
+			str := "a string"
+			if str == "another string" {
+				return 1
+			}
+			return 0
+		}
+		`,
+		big.NewInt(0),
+	},
+	{
+		"compare equal ints",
+		`
+		package testcase
+		func Main() int {
+			x := 10
+			if x == 10 {
+				return 1
+			}
+			return 0
+		}
+		`,
+		big.NewInt(1),
+	},
+	{
+		"compare not equal ints",
+		`
+		package testcase
+		func Main() int {
+			x := 10
+			if x != 10 {
+				return 1
+			}
+			return 0
+		}
+		`,
+		big.NewInt(0),
+	},
+}