XCF File Reader

Designed for extracting layer and pixel data from XCF files.

I originally made this as part of an art pipeline for a game idea, as such it's missing support for a lot of features (I only needed to pluck pixel data from a few layers).

• results are always returned in RGBA pixels, regardless of original format
• supports RGB or RGBA images, but not grayscale or indexed
• XCF files with better compression are not supported (there is an ignored failing test for this, should someone like to add support)

Contributions welcome.

Example

```rust extern crate xcf; use xcf::Xcf;

fn main() { let mut rdr = File::open("untitled.xcf") .expect("Failed to open file."); let raw_image = Xcf::load(&mut rdr) .expect("Failed to parse XCF file.");

// or simpler yet:
let raw_image = Xcf::open("untitled.xcf")
    .expect("Failed to open and parse XCF file.");

} ```