Fix broken backward compatibility with output file path

[kotas]

For issue #17

By changing the strategy how to capture output files from tsc in
7156ee4, path of output files changed
accidentally in some cases. This commit fixes it.

When input paths have any common path, tsc skips that common path
and uses only different part of the path for output files.

For example, if we have "foo/bar/a.ts" and "foo/bar/baz/b.ts", tsc skips
"foo/bar/" automatically and outputs "a.ts" and "baz/b.ts". gulp-tsc
followed that rule implicitly by changing the strategy.

However, this is not ideal for gulp tasks since with gulp.src("foo/*/.ts")
the plugin should use "bar/a.ts" and "bar/baz/b.ts" for output paths.

To fix this, we add common part of input paths to output paths.

[bestander]

Hi, thanks for the best gulp tsc task.
I think this pull request broke my build and I reverted to version 0.5.0.

This is my setup:

gulp.task('compile-typescript', function() {
    return gulp.src(['app/**/*.ts'])
        .pipe(cache('typescript'))
        .pipe(typescript(typescriptOptions))
        .pipe(gulp.dest(webOutputPath + '/app'));
});
gulp.task('dev', function(callback) {
    runSequence('clean-web-output',
        ['compile-typescript', 'compile-sass' ],//, 'run-tests'],
        function() {
            gulp.watch(['app/**/*.ts'], ['compile-typescript']);
        });
});

If I change one TS file I expect 1 or more JS files to be compiled into my .tmp folder.

For example if I change:

/app/online-reader/popup-reader-directive.ts

Then compiler produces this list:

<tmp>/online-reader/popup-reader-directive.js
<tmp>/online-reader/reader-preferences-service.js
<tmp>/analytics/http-latency-sampler.js

The change in this ticket changes it to:

<tmp>/online-reader/online-reader/popup-reader-directive.js
<tmp>/online-reader/online-reader/reader-preferences-service.js
<tmp>/online-reader/analytics/http-latency-sampler.js

Which os wrong.

I am happy to debug or provide more test data.

[kotas]

@bestander Thank you for your report! I've made the issue above for the problem. It'll be considered to be a bug.

[kotas]

@bestander I've published v0.6.0. Please check if it fixes your problem. Thank you!