[BUG] Registering FSI Printer has no effect

**Describe the bug**

Registering fsi printer has no effect:

```
val it : FSharp.Stats.Matrix = matrix [[0.1; 2.0]
[0.1; 2.0]]
```

**To Reproduce**

```fsharp
#r "nuget: FSharp.Stats, 0.4.0"
open FSharp.Stats

fsi.AddPrinter(FSIPrinters.matrix)

matrix [[0.1;2.];[0.1;2.]]
```

**Expected behavior**

```
0 1
___________________________
0 | 0.100 2.000
1 | 0.100 2.000

```