Normalize URLs on-the-fly when comparing

[mickael-menu]

Normalize URLs on-the-fly when comparing

Normalize URLs when comparing them following these rules:

• Scheme is lower case.
• Paths must only percent-encode required characters.
• Relative paths (e.g. ..) are resolved.

The reason for this change is that some EPUBs encode unreserved characters which breaks locating a Link from an HREF.

For example both of these are valid relative URLs which point to the same resource:

• Text/Ces_choses_qu'on_laisse.xhtml
• Text/Ces_choses_qu%27on_laisse.xhtml

URL and Media type in Link and Locator objects

Locator and Link objects now use AnyURL and MediaType instead of strings.