Convenience function, checks that a $uri string is well-formed by validating it but not returning an object. Returns TRUE if $uri is a well-formed URI, or FALSE otherwise.
Create a new Microsoft_Uri object for a URI. If building a new URI, then $uri should contain only the scheme (http, ftp, etc). Otherwise, supply $uri with the complete URI.
Constructor accepts a string $scheme (e.g., http, https) and a scheme-specific part of the URI (e.g., example.com/path/to/resource?query=param#fragment)