RFE: Graph navigation keys

There are some things that will be interesting to have in the interactive graph view:

• Scroll/seek to the first block (entry)
• Iterate over all the blocks that have no out edges (end/exit nodes)
• Iterate over all the blocks that have a jump back out edge (loops)
• Iterate over all nodes that have more than 2 out-edges (jump tables)

We can probably show that in a list in the left side of the screen with "points of interest" for the current graph