Add language specific special characters in database configuration for usage in editor

Goal:

• The current bar in the editor, that enables adding special characters (currently non-breaking space, carriage return and tab) is extended by characters, that can be defined in the configuration
• The characters can be defined language specific (different characters per language)
• The configuration will be overwriteable on client, task-import and task-level

At the current stage of implementation no configuration in the GUI will be possible,  because this is to much effort for the current budget by the client. So configuration will only be possible on DB-level. Overwritablilty on the different levels will therefore only be prepared in the back-end, but not usable so far.

Implementation

• One additional configuration option is provided in the system configuration for this feature
• The configuration will be overwriteable on client, task-import and task-level
• The DB structure for the config should contain the following data

• • target language for which special characters are defined
  • defined special character as unicode codepoint (this is how it has to be entered, when editing the config)
  • defined special char visualized
  • As target languages all available languages in translate5s LEK_languages table can be used
• If there are special chars defined for a language, they will be added as icons to the special chars bar in the editor, if that language is the current target language of the task
• the character itself will be shown on the button

Please use the list in TS-972 as default list.