- Further debug printing statements added

This reverts commit 5a558807.

The code was meant to leave the first row empty for the text, but ended up drawing the "histogram" one row shorter

- hammer-parse-apply wasn't clearing the pointer to the desired stack frame
- Reproduction steps: hammer-parse-step N, hammer-parse-apply, hammer-parse-step 1

- Also fixes double curly braces when printing HByte structs when len is 0

Add tests for .set_top_node(0, None), and .set_top_node(None, None)

Also ensure cleanup runs in HParseResult test