Refactor Persisted state
Refactor dirty/transient state handling
Extend specs for Session::Relation#new
Simplify IM
Kill Session::Relation#track mutation
Fix Guardfile
Enable tmux notifications in Guard
Refactor spec for Session::Mapper#load
Refactor Session::Mapper#load and kill remaining mutation
Rename Session::IdentityMap.new => .build
Simplify Session::Relation#new signature and kill mutation
Simplify Session.start signature and kill mutation
Add Session::Environment.build
Add Tracker#store_transient
Re-add explicit block to Session::Relation#new
Add specs for state predicate methods
Make Tracker#store private
Add specs for Tracker#store_transient
Add specs for Tracker#store_persisted
Introduce Session#clean? and kill more mutations