Fixes for mspaint

1- I suggest to declare haccel as an HACCEL rather than HANDLE and avoid the later cast, there is no need to not do so.

2- There are handle leaks after reading the keys from the registry, so I added calls to RegCloseKey() where it is needed. I also suggest to use a function ReadFileHistory() and empty the file name if the key is not found or if an error occured.