adding dijkstra(..) - find shortest path in graph

one test fails.
next: add subfunction to clean up code
added subfunction to make code clearer. test still fails.

next: fix algorithm
fixed algorithm - test passing.

next: add more tests
added more tests. working.

next: clean up code more, add more tests
added diamond test.

next: separate Simple to GraphSimple.java. visit TODOs. update readme.
added GraphUndirected. all tests passing.

next: move algorithms to separate package
moved algorithms to separate package, with Search and Sort.java

next: add logging, update readme. add A* or TSP or radix sort