Classes:
- LINQ::DBI
- LINQ::LibXML

Optimization:
- select_many: avoid to_list
- skip/skip_while: create an iterator
- sequence_equal: avoid to_list
- any: short-circuit true, avoid to_list
- all: short-circuit false, avoid to_list
- contains: short-circuit true, avoid to_list
- zip: avoid to_list

Features:
- LINQ::Collection->to_array ought to return a tied array pointing back to the collection
- LINQ::Util::columns:

	$data->select( columns(
		'name',
		'telephone', -as => 'phone',
		sub { ... }, -as => 'address',
	) );

	$data->where( column_assertions(
		'name',    -is => 'Bob',
		'age',     -is => 30, -cmp => '>=',
		'country', -in => [ 'UK', 'USA', 'France' ],
	) );
