Increase cost of DOME from 1600 to 1800

Just move this slightly later, and make DOME-first rushes a bit more
risky.
Merge pull request #4810 from chrisforbes/delay-dome-balance

Adjust RA balance
Add changelog entry for Radar Dome cost tweak.
Merge pull request #4857 from pchote/ra-balance-changelog

Add changelog entry for Radar Dome cost tweak.