Remove TODO comments
logger_test.go: Remove stdout output
logger_test.go: Change %s to %q in expect output
logger_test.go: Rename TestFlagsLdate
logger_test.go: Rename TestFlagsLfunctionName
logger_test.go: Fix newline stripping with no Lansi

When Lansi was not used, output prefixed with newlines was stripped. Fix the
error and add TestFlagsNoLansiWithNewlinePadding.
logger_test.go: Refactor TestPrefixNewline