A simple variable-sized bitmap.
Most of the bitmap implementation I found on crates.io are either fixed-size or compressed which isn't what I needed for my project. I want a growable bitmap that is expected to remain small. A compressed bitmap adds a lot of additional data structures on top of the bitmap itself which works great for large bitmap but adds a lot of unnecessary complexity for bitmap that is expected to remain small.
```rust use var_bitmap::Bitmap;
let bm = Bitmap::new(); bm.push(false); bm.push(true); bm.push(false); bm.get(2); // Should be false bm.set(2, true); bm.get(2); // Should be true ```