Create Import wizard for pre-calculated season/league statistics

[SSchulze1989]

Is your feature request related to a problem? Please describe.
If a league has pre-existing seasons that are not managed within this tool, a import functionality is needed for having the required statistics data available.

Describe the solution you'd like
Import could be done through a csv (or similar format) that holds the statistic values prior to the first managed season inside the league manager. There should be a wizard to guide through the import steps:

• select columns for matching csv data to iRLM data
• if needed specify factor and offset for numerical values
• perform validty check and secure that the imported data is formatted correctly so that future statistics can be calculated.