Lets stop Dimming non-arrays

I've brought this up before I think, but I think it would be easy and useful for new VB users and converts from other languages to accept VB if this one keyword (Dim) could be avoided.
```
Let s As String = "A" ' Let reads better when a variable is not an array
Var p As Point ' Var reads better when you don't have an initial value to assign
Dim a(0 to 9) As Byte ' And this still reads OK for arrays
```
One argument is that we might want Let to be used for immutability, but I don't think that's a good idea, because it's not readable. Better would be to allow ReadOnly modifier for variables.
```
Let ReadOnly x = Fetch("stuff")
ReadOnly Var y = Load("stuff")
ReadOnly y = Load("stuff") ' Could leave off Let and Var because it reads fine without.