add implementation notes to dmain2.d
refactor src/rt/minfo.d
Merge pull request #575 from WalterBright/add-dll-notes

add implementation notes to dmain2.d
Merge pull request #578 from WalterBright/refactor-minfo

refactor src/rt/minfo.d
tweak message
Merge pull request #579 from monarchdodra/tweakRunner

tweak test_runner message