ShellItem not released on error in Windows implementation

[demurgos]

Hi,
The following ShellItem is not released if an error is returned while using it (the function jumps to the end):

nativefiledialog/src/nfd_win.cpp

Line 403 in 5cfe500

::IShellItem *shellItem(NULL);

Similarly, the file dialog itself is never released.

Compare it to the official example.

[mlabbe]

I agree, this needs doing! If you offer a PR, I would be happy to merge it.

https://github.com/mlabbe/nativefiledialog/blob/master/docs/submitting_pull_requests.md

[mlabbe]

Friendly bump. If you have any time, I'd appreciate it.

[demurgos]

Thanks for the reminder.
I have a busy period at the moment and I'm not sure I'll be able to do it in January. I'll send a PR once I have more time.

[MrSapps]

Could maybe switch to use the RAII objects - the ComPtr would auto call release in any circumstance

[mlabbe]

I implemented a fix for all of the cases on the devel branch.