Added a -depends switch which outputs a dependency line suitable for

* Added a -depends switch which outputs a dependency line suitable for a makefile" (by @adamgundy: 10696d9c11afccd7fb4dadd92985b5166c66f6f2)

* Added a synonym flag "-M" to "-depends" to match syntax of other compilers.
* Added support for recursive dependencies.
* Fixed some issues with path calculation when dependencies and recursive dependencies.