Template type instances generated in separate modules do not generate include statements in C code

[alexnask]

Here is an example in some code I've been writing:

UnsafeArray.ooc

UnsafeArray: cover template <T> {
    data: T*
    length: Int

    init: func@ (=length) {
        data = gc_malloc(T size * length)
    }

    operator [] (i: Int) -> T {
        data[i]
    }

    operator@ []= (i: Int, t: T) -> T {
        data[i] = t
    }
}

Bitmap.ooc

import ../UnsafeArray

RgbColor: cover {
    r, g, b: UInt8

    init: func@ (=r, =g, =b)
}

Bitmap: class {
    width, height: Int
    data: UnsafeArray<RgbColor>

    pixelCount ::= width * height
    /* ...  */
}

This piece of code generates invalid C code because the generated template instance does not have access to RgbColor's declaration.

Rock should automatically deduce what additional imports are needed and add them to the template type's module.

[alexnask]

Temporary fix is obviously adding imports manually (e.g. import Bitmap in this example)