Add warning if files is omitted from tsconfig.json

[jbrantly]

All files in the directory and subdirectory are included if files is omitted from tsconfig.json. This typically results in some errors of some sort as all kinds of crap can get added (TypeScript lib files, for instance). I think it might be useful to detect this condition and just print a simple warning.

[OldrichDlouhy]

In TypeScript 1.6 there is an option to exclude directories when you do not specify the files property - see microsoft/TypeScript#3043. So if this is implemented it needs to take the exclude property into acount.

[jbrantly]

Good point. FWIW, exclude does already work in ts-loader, but you're definitely right that any warning message would need to take that into account.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

Closing as stale. Please reopen if you'd like to work on this further.