Update side-nav.tmpl to properly parse event hashes

The regexp did not properly match a JSDoc3-Compliant `@event` name.

`Hurl#event:snowball` becomes:

1.	`Hurl`
2.	`#event:snowball`
3.	`event`
4.	`snowball`

**Prior:** `Hurl#event:snowball.html`

**Fixed:**  `Hurl.html#event:snowball`

*Warning: No tests have been published, therefore, this could break something else.*