Improve the mailbox

[GuestUniverse]

I want to quote myself…

Colosseum station (+ little rant about mails)

I think we can split the inbox into multiple sections similar to the “Favorites” list: Challenges (marked by a rocket): Daily Challenge, Weekly Challenge, Space Race, Flight Test: BX-6 Heavy Bomber, Key Rush Test. Top-10 lists (marked by trophies): Top-10 reward for Daily Challenge, Weekly Challenge, Space Race, Most Active Recruit (Daily), Most Active Recruit (Weekly). Squadrons (marked by squadrons icon): Invitation messages that leaders of the squadrons send you, Most Active Squadron (end o…