duckscript v0.1.7

• Fixed runner to return an error if on_error requested crash or exit and not just end the script.
• [Breaking Change] Unalias can remove aliases not created from the alias command.
• New properties read/write commands #61
• Default command run implementation should crash and not error #63
• [Breaking Change] Invoking a command that does not exist should crash and not error
• cat command to support multiple files #62
• New debug commands (dump_instructions, dump_state, dump_variables) #58 #59 #60
• Running duck cli without arguments, stars up the repl mode #41 #42