Change IO model
Rename PathSearchResults to OneToAllPathSearchResults
Extend PathSearchNode with child (previous) node
extend OneToAllPathSearchResults respectively
Add AllToAllPathSearchResults class
Fix return type annotation for dijkstra and bellman-ford
Fix dijkstra, bellman-ford, backtrack
Add newlines at the end of file
Add print_matrix method to IO
Implement Floyd-Warshall
Import different types of graphs via aliases
Fix spelling mistake in method name
Implement 1st part (Floyd-Warshall