Emit error codes when reporting diagnostics.

[DanielRosenwasser]

Addresses part of issue #506.

Before:

file.ts(1,6): ';' expected. 
file.ts(1,11): ';' expected.

After:

file.ts(1,6): error TS1005: ';' expected. 
file.ts(1,11): error TS1005: ';' expected.

[mhegazy]

+=

[mhegazy]

👍

[CyrusNajmabadi]

Does 'category' need to be localized?

[DanielRosenwasser]

Apparently not!

[sheetalkamat]

Please do not checkin this change without change to https://github.com/Microsoft/TypeScript/blob/printDiagnosticCodes/src/harness/harness.ts#L776

Also I would recommend making the changes to https://github.com/Microsoft/TypeScript/blob/printDiagnosticCodes/src/harness/harness.ts#L791 such that it calls minimalDiagnosticsToString here itself instead of from runners (eg: https://github.com/Microsoft/TypeScript/blob/printDiagnosticCodes/src/harness/rwcRunner.ts#L155 and https://github.com/Microsoft/TypeScript/blob/printDiagnosticCodes/src/harness/projectsRunner.ts#L302)
its important that compiler runner emit the error code so there is a way to verify error codes when someone add/modifies error codes.

[CyrusNajmabadi]

👍

[DanielRosenwasser]

@sheetalkamat I made the change to minimalDiagnosticsToString - I agree that we should make a general change to emit error codes; however, that seems like a change that will make this PR a bit difficult to digest.

[sheetalkamat]

I would either do compilerrunner change as a separate iteration of this same pull request (I prefer that) or create a separate pull request for the same, But given that now we are showing error codes in error that change should be done sooner than later.

[DanielRosenwasser]

Will do. I'll start working on it. Thanks!