flutter_package / flutter_screenutil

Features/Bugs:
- Feature: You can select what classes needs to be rebuilt instead of rebuilding everything, if you have widget A, either addi SU mixin or add 'A' to list ScreenUtilInit.responsiveWidgets
- Feature: Using ScreenUtilInit.builder is optional (use it only when using library in theme)
- Bug: Second call to ScreenUtil.init ignores any existing values and uses the default values when not provided, use ScreenUtil.configure instead
- Bug: ScreenUtil.ensureScreenSize raises an overflow error

* bugifx: 某些情况下键盘无法弹起

* update readme

Co-authored-by: Daniil Makeev <daniil.makeev@alfatraining.de>

* Fix error when assigning MediaQueryData

* Fix condition statement

* Apply null-check

Co-authored-by: cordy <cordy@blinghour.com>