More information in Error for debugging : line numbers

For certain errors Bule does not output info needed for tracing the problem like line number and file name.  

Example: 

File: 

```
#ground a[12]. 

a[Y] :: #ground b[X]. 
```

running Bule outputs: 
```
Fatal error: exception Bule2.Circuit.UnboundVar("X")
```
 missing line number and more. 
