Continuing Meteor Rework

- Most events now have lower and upper bounds. ETAs, number of meteors,
wave delay, you name it
- Bar supplies vastly extended and spawn system mostly unfucked
- Changelog included
- Minor map modifications to include new spawnpoints (landmarks)
- Included is the -commented- line announcement in meteor.dm and the
announcements.txt file ready for generation. To activate, simply
generate then uncomment line 31 of meteor.dm
Consider for(var/i=0;i<X;i++) loops