Improve handling of blender.addon.moduleName

[Mateusz-Grzelinski]

• using blender.addon.moduleName with extension sometimes fails to create directory and creating link fails
• improve "blender.addon.moduleName": "auto" to automatically convert basic invalid python modules names like: -,.!@#$%^&*() (especially hyphen is used in directory names often to _. Would fix simple mistakes like Error when starting Blender #192
• review if we can display error message if python module name is invalid
• add basic validation to blender.addon.moduleName so that user can not specify invalid python id - just fail is any of chars are present -,.!@#$%^&*()