Move out command parsing from the session to the frontend.
Add partial program command parser and executor.
Refactor out command line parsing into new classes. Move default CLI into a new class.
Fix core option parsing in the CLI interface. Make command processors execute on a session just-in-time.
No need to set args to None in the command line interface; examine args length to early-abort if needed.
Clean up CLI command parser for the PROGRAM command, move file section fetch to an internal function.
ELF Format: Abort if an empty ELF file is given.
Merge branch 'command_parsing'