Asynchronous Player - Vector assertion failure

[kringej]

There were some discrepancies I found in the master code branch on GitHub. When I fixed them, the player_async still had a problem and couldn't play my midi file:

File: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.33.31629\include\vector
Line: 1758

Expression: vector subscript out of range

The synchronous player example code needs to be updated also. The include file name and the command to start the player are wrong. It should be PlayerSync.

In windows.hpp, namespace should be output with a lowercase "o".

[kringej]

Also there was no member variable _connected in windows.hpp, so I added one:
bool _connected = false;

[kringej]

PlayerAsync::~PlayerAsync() {
if (thread_) {
if (thread_->joinable()) thread_->join();
delete thread_;
} //! @fixme
}