Add docs for DataMapper::Environment
Add docs for DataMapper::Relation::Aliases
Add docs for DataMapper::Relation::Aliases::Index
Add docs for DataMapper::Relation::Aliases::Strategy
Add docs for DataMapper::Relation::Aliases::Attribute
Rename a local variable in Aliases.index_entries
Extract private Arel::Edge#projected_attribute
Change formatting in Arel::Edge#join_relation
Change formatting in Veritas::Edge#join_relation
Add & Remove a unit spec for Relation::Aliases#each
Align Aliases#index specs with Aliases#each specs
Fix Aliases::Index#rename code and specs
Fix unit spec for Veritas::Node#join
Raise on self joins with invalid relation aliases

This is a first step towards supporting (in)direct
self joins.
Fix expectations in pending Aliases#index specs
Simplify private Aliases::Index#renamed_entries
[arel] Add new spec for loading an object without its association
Fix spec for jruby
Move Attribute out of the Mapper namespace

Reasoning: attributes can work on their own, they aren't mapper
"internal part". In fact attribute are mappers as well but on the value
level. So, you can use an attribute mapper standalone, it should live in
the top level namespace.
Premature git add is premature