Handle Go line directives correctly

[GoogleCodeExporter]

The Go compiler understands line directives (aka line comments), like "//line 
path/file.y:123", and prints both source locations when reporting errors:

e.g.:
path/file.y:123[/path/to/actual/file.go:321]: here comes the error message.

See 
https://code.google.com/p/go/source/browse/src/pkg/go/scanner/scanner.go?r=30444
b809a9e15ff76ca49afe155fac2b0e5e979#146

Please make GoClipse support these error messages. It currently lists all 
errors in /path/to/actual/file.go, but does not know how to set the correct 
line number.

Original issue reported on code.google.com by fo...@google.com on 12 May 2013 at 6:21