Update CrashSite outposts

[RedRafe]

Changes

A. Add outposts maximum level

outpost_data for outpost builder will now also accept 2 optional parameters:

• maximum_level_count: number
• maximum_level_formula: token id to function callback

Both will try to set maximum_level and if set/reached, it wont be possible to upgrade the outpost further.
I have decided to simply disable the upgrade item instead of removing it completely as this option keeps open the possibility to develop further the feature in the future, without adding/removing market item every time.

Following Tigress and CrashSite veteran players feedbacks, Spawn Market in CS has been capped at Lvl.6 for multiplayer events

B. Fixed that outposts would display rendering text incorrectly

C. Slight GUI style update to Retailer

[grilledham]

Looks good.