[WIP] 🚧 Support of issues management

[guyzmo]

Implementing support of issues (only for github ATM) (cf #104)

git hub [<user>/<repo>] issue ls: lists all issues for given or current repository git hub [<user>/<repo>] issue ls <issue_id>: shows details of given issue git hub [<user>/<repo>] issue ls [mark|labels|milestone]: list accepted values for action git hub [<user>/<repo>] issue get [mark|labels|milestone]: gets value for given action git hub [<user>/<repo>] issue set [mark|labels|milestone] <value>: sets value git hub [<user>/<repo>] issue unset [mark|labels|milestone] <value>: unsets value git hub [<user>/<repo>] issue toggle [mark|labels|milestone] <value>: toggles value git hub [<user>/<repo>] issue edit <issue_id>: launch $EDITOR to edit given issue_id

• Bulk actions
  • for list, set, unset, toggle a search can be done with a similar query as github's to run bulk actions, using --filter=<filter> where <filter> is a comma separated list of action, values with the action being one of mark, label, milestone:
    • --filter="label:bug, label:in progress, milestone:1.2
    • special values are:
      • milestone:* for all milestones
      • state:all for all opened and closed issues
  • alternatively, a list of issues can be provided for get, set, unset and toggle
• Parse mails
  • if <issue_id> is - stdin will accept a mail message, and look for githubs Message-IDpart to extract/and<issue_id>` from it.

fixes #104