Merge block and line underflow functions

[jfroelich]

Stepping back and looking at the initial implementations, they are largely the same function. I now find myself routinely wanting to make changes to both functions at once. It would be simplifier if both were just one function.

This means I need to step back from the block-only or line-only organization of the code.

[jfroelich]

Done, recent commit did this, forgot to reference the issue.