Released netscript version 1.6.5. (security notice)

main focus of the release is the fixing of a potential local/remote security bug, found during a quick audit. this security is somewhat minor, due to the fact it relys on the users ruleset. for more information, review the changelog. also, added the $` variable for execution data manipulation, and changed --hist option to only add if the line does not already exist in the history file.