Client authentication file names

Modules
	Client command-line processing
	Client argument processing.
Authentication information file names
Names of files that contain authentication information. These filenames are decided by libsvn_client, since this library implements all the auth-protocols; libsvn_wc does nothing but blindly store and retrieve these files from protected areas.
#define	SVN_CLIENT_AUTH_USERNAME   "username"
#define	SVN_CLIENT_AUTH_PASSWORD   "password"