stop using std::aligned_storage_t

appveyor: do not override clone_script

make uses_allocator specialized for all function

supports uses-allocator construction

Fix warning for windows

Correct my previous commit

Improve the previous commit not to use union aliasing

Fix issue #21

chore: silence Visual Studio 2022 (17.3.0) warning

Fix issue #50

Add option to limit empty callable propagation to known types

Apply clang format

allocator: rename to avoid shadow warning

Release 4.2.0

fix: use proper doxygen syntax