Support CombatSettings block

[Rider-Linden]

Description

Support the optional CombatSettings block in the RegionInfo. Only needs to be processed when setting up the Region tab in the Region/Estate floater (LLFloaterRegionInfo::processRegionInfo) other processRegionInfo methods have no use for the data.

Format for the block is:

    {
        CombatSettings  Variable
        {   CombatFlags         U32         }
        {   OnDeath             U8          }
        {   DamageThrottle      F32         }
        {   RegenerationRate    F32         }
        {   InvulnerabilyTime   F32         }
    }

and it should follow the RegionInfo5 block.

Relates to: https://github.com/secondlife/server/issues/968