Make the e-ticket easily editable

[BigAndini]

Infos:

• Version: 0.5.58

Actual behavior:

• if somebody wants to edit the e-ticket it's much coding and really not easy.

Expected behavior:

• have a texteditor where you can simply put in the text that appears on the e-ticket
• have a column to list all available variables that can be included into the e-ticket (config.name_short or participant.firstname or package.code)