Implement `:w:p` to format numeric values

[CHiPs44]

Allow to specify width and precision when displaying numbers:

...
Var
    Sum: Integer;
    Total: Real;
Begin
    WriteLn('Sum=', Sum:8);
    WriteLn('Total: ', Total:10:2, ' €');
...

Does it work for strings ?

Allowing negative width to left align instead of right would be great but is explicitly disallowed in FPC docs (https://www.freepascal.org/docs-html/rtl/system/write.html).

"Real numbers are, by default, written in scientific notation"