Release 0.3.0

New code generation for the safe bindings based on the syn crate. This uses lvgl-codegen directly, which implements code generation for known patterns. This avoids a lot of manual work to expose LVGL API as safe Rust API.

Improvements:

• Code generation is completely transparent to users;
• No (direct) dependency on clang-rs;
• The code in lvgl-codegen gets cleaner and intuitive to write, since now we are processing Rust code instead of C. C is completely abstracted at the lvgl-sys/rust-bindgen level;