Some minor changes in this commit includes the usage of
std::unique_ptr for the Pimpl-idiom in steam::SteamAPI class and
renaming the SteamAPI::initialized() to SteamAPI::isInitialized() to
avoid confusion reading the code.
Forum post:
https://steamcommunity.com/app/431730/discussions/2/7260435303111061192/
Steam API/DLL now contains a SteamAPI_InitSafe() function for backward
compatibility similar to the old SteamAPI_Init(). The official
"steam_api.h" header file contains inline-defined functions for
SteamAPI_Init() and SteamAPI_InitEx() but both use the published
SteamInternal_SteamAPI_Init() function (we don't need it, I guess, so
SteamAPI_InitSafe() is enough for us).
It looks like a Steam clien bug on OS X, it activates Aseprite window,
and then Steam is activated again, so the Aseprite window lost the focus
and is left below the Steam window.
