- client and API: add gpu_usage field to APP_INIT_DATA,
    so an app can find out what GPU fraction it's expected to use
Updates for 7.0.58
Merge branch 'master' of ssh://boinc.berkeley.edu/boinc
Merge branch 'master' of ssh://boinc.berkeley.edu/boinc
- Manager (Win): case-insensitive check for .exe ending of exclusive apps
- client: if <dont_check_file_sizes> is set in config, still check for
   errors (e.g. verify failures) at startup, and reset file if so.
   Otherwise we'll never recover from those errors.
- client: rename two different functions named backoff()
    to make it easier to see what's going on.
- fix code formatting in manager