Currently if a file is partially written to (eg, the file is opened for
writing but the write fails), the updater won't correctly roll back to the
previous version, leaving the OBS install in an inconsistent state.
We now track failed installs or hash failures on patched files with a new
STATE_INSTALL_FAILED state and properly roll back on errors.
When updating large files such as libcef, the patching process can take a
decent amount of time. Previously the progress bar would remain at 100%
after completing the downloads, so the user may think the updater has
frozen. Now it shows the process of the install / patching process.
This would cause people to download the 64bit files when they were on
the 32bit version of windows, even though those files aren't meant to be
installed.
The GetTempPath and GetTempFileName functions weren't being used
correctly, GetTempFileName always create a temporary file, and was
creating a temporary file in the root directory of the hard drive
unintentionally.
