- ASTManager helper class to hold the top node of the ast to be printed
- HDoParseRetBreakpoint
- ast printing commands
- Update BreakpointManager tests with HDoParseRetBreakpoint tests
- Add support in TopLevelParse to select a stack item for printing the AST node of

It has been moved to top-level-parse.py

Fix breakpoint_manager not using its own retq finding function

Looks like there's a lot of duplicated code for the refactor
to clean up.

Finally, instead of having to hardcode a constant, the length of
the code to disassemble in search of a RET instruction is discovered
at runtime.

Increased the range of instructions a RET is searched for.
TODO: more robust error handling, see if there's a way to search up to a function's end via the GDB API

"hammer-parse-stop-at-input-pos" is correctly "hammer-parse-stop-at-pos"