Tracking issue for 0.7.0

[nia-e]

Absolutely necessary:

• Close Can this crate work with gtk ?  #103
• Merge [WIP] Rust-native config file(s) for LVGL #82 <=> Close Make it possible to define LVGL config in a higher level format #11
• Close Cross support tracking issue #78
• Close Automatic tests for non-x86 compile #73
• Close Tracking issue for proper memory management, dropping, and threading #140
• Finish up bindings to more LVGL features

Maybe:

• Close Attribute macros for lvgl-rs #68
• Close Expose Rust Global Allocator to LVGL C code #49
• Close Make possible to define styles as CSS #1 (quite optimistic, I don't know anything about CSS)

If all that is finished:

• Close Tracking issue for lvgl-codegen and general code generation rewrite #100

[nia-e]

Given that there have been some (relatively major!) bugfixes and fixed functionality since 0.6.2 to the point where it's pretty fundamentally broken, should we version bump 0.7 soon and move these features for 0.8? Semver says we need to bump minor version because of breaking changes

[nia-e]

cc: @rafaelcaricio

[nia-e]

This thread suggests that it would be fine to release the current changes as 0.6.3 (if a bit weird). They mostly fix functionality and/or implement things that should have been there and were mostly my oversight but idk