Profiling struct generator

Yet another generator for gl_generator, very similar to DebugStructGenerator, but with these changes/additions:

• It does not log all calls. It only logs a call that caused an error.
• The corresponding explanation is included with the error code.
• Contains a profiler that tracks the number of GL calls and errors.

Using the profiler

The generated gl module gains 3 additional methods:

• profiler_reset() - resets the profiler;
• profiler_call_count() -> usize - returns the number of calls since the last reset (or application start);
• profiler_err_count() -> usize - returns the number of errors since the last reset (or application start);

Example usage:

```rust gl::profiler_reset();

// the code

println!("Number of GL calls: {}", gl::profilercallcount()); println!("Number of GL errors: {}", gl::profilererrcount()); ```

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.