--native-lib

While we're changing the commandline implementation, I think we should review our definition of "native library".

ATM we have:
- `haxelib path` can return `-L` for native neko libs. There's no other way to inject them
- Flash have `-swf-lib`, C# has `-net-lib` , Java has `-java-lib`

I propose regrouping all of the there under a single `--native-lib` (with aliases to older `-swf-lib` etc.), and have a single `com.native_libs`.