Renamed xclipMode->clipboardMode and added a "disabled" setting for it
Added --set for temporary config overrides

This deprecates --git and disables --no-git.
Also replaced the --xclip-clipboard compatibility message (and logic)
to use the new --set parameters.
Cleaned up --help
Don't use --no-git in tests
Sandbox the tests into a temporary $HOME
Detect and handle a user having no gpg keys
Added tests for error conditions
Handle missing parameter for 'git'
Added additional tests for error handling
Added a test of already upgraded dbs
Don't write _-prefixed conf values

Also added information if --set has been supplied when outputting
configs to stdout
Corrected paths in FILES

Also documented the dataPath option in gpgpwd.conf
Added config info to --debuginfo