Version 1.91.7 of the imgui library with the cimgui wrapper.
imgui allows us to easily create minimal and powerful UI for
use-cases like in-game overlays or separate tooling.
The additional wrappers cimgui_impl_dx9 and cimgui_impl_win32
were added to provide a full C linkage integration for the rest
of the code base.
Tweaks to the makefile were kept to a minimum but enable
compilation of C++ since imgui is C++ based.
Remark: At this point bemanitools itself is still to be kept a pure
C codebase. Due to the lack of proper module/library management
with the current build system in bemanitools 5, proper separation
of concerns and clean integration with external libraries isn’t
possible with reasonable effort.
