Reorganize some project files
Add selected node + expand/collapse concept
Highlighted selected line
Beginning of next/prev tree traversal algorithms
Extract TextVisualizer specs
A single basic spec for the "next node navigator"
Test expansion traversal + fix bug
Check more traversal cases + fix root handling bug
Add required stringio
Fix previous traversal + specs
Add missing require
Fix swapped j/k keys
Indent + correct expansion strings
Don't assume same CSV field position every time