@:include meta, accept multiple headers

Hi!

Sometimes, extern classes need to include more than one header.
The current solution will be to create a separate header that will contain all required headers and then include it into Haxe extern class.
Like this: `@:include('./Headers.h')` which is contain `HedaerA.h` and `HedaerB.h`

But, it would be nice if `@:include` will accept multiple headers out of the box, something like:
```haxe
@:include('HedaerA.h', 'HedaerB.h')
extern class Native {}
```
or
```haxe
@:include('HedaerA.h')
@:include('HedaerB.h')
extern class Native {}
```
Thank you!