Improve error reporting: add an url with more info for each warning/error

I think it's possible to add, unobtrusively, a short link to more info for each warning/error message

like

```
error FS0001: The type 'int' does not match the type 'int -> int' ( http://fsc.fsharp.org/FS0001 )
```

Write a good **context sensitive info help fix the error**, but **a good link help to study in deep the issue** because can contain code examples, more urls, long description, etc and that's the second choice if the error message is not enough (for example new users)

That's should be good also for tooltips, because urls can be converted to links easily in every ide, or automatically in lot of editors.

Also is going to be really nice for search too, because for example googling for [fsc error FS0001](http://lmgtfy.com/?q=fsc+error+FS0001) give some info (and the 5th link is the amazing fsharpforfunandprofit tutorial) but is mixed with other errors

ref #1103