Feature/configurable_rank_management

[IlmLV]

Two main changes:

• allows to keep manually set higher ranks - this is high value option for server admins who previosly didn't used TSN-Ranksystem and was manually setting user ranks OR if online time is not the only way to earn higher ranks
• allows to use forced single rank group usage - if any of cases user currently has more than one ranksystem group, all, except one higher ranked, will be removed

Both rank management options is defined in Core settings section, where thoes can be enabled, by default they are disabled - works by previous behavior.

[IlmLV]

updated to 1.2.11 and cleaned up merging mess