...in preparation for non-source locations, i.e. locations that don't come
frome source buffers.
No functionality change, but a fair bit of SourceManager API and idioms have
changed.
Swift SVN r18942
Previously, the frontend detected that its output was being piped into the
driver and buffered, and decided that that wasn't a color-friendly output
stream. Now, the driver passes -color-diagnostics to the frontend to force
color output if the driver itself is in a color-output context.
<rdar://problem/16697713>
Swift SVN r18506
integration
Motivation: libIDE clients should be simple, and they should not have to
translate token-based SourceRanges to character locations.
This also allows us to remove the dependency of DiagnosticConsumer on the
Lexer. Now the DiagnosticEngine translates the diagnostics to CharSourceRanges
and passes character-based ranges to the DiagnosticConsumer.
Swift SVN r7173
