smbclient_create: add some basic testcases
Force modern, full timenames when getting xattrs

The old time names are most likely a legacy feature; choose not to
support them here. Use only the more modern and comprehensive time
names.
smbclient_option_(get|set): add functions
Options: add some basic testcases
smbclient_option_(get|set): add documentation
Options: tests: add NTLM hash test; change guest access to "no"

For the NTLM hash test, we need to set the "guest access" flag in the
Samba setup to "no", otherwise we're allowed to connect anonymously.
smbclient_(library_)version: add functions, documentation and tests
smbclient_(f)statvfs: add functions, docs, tests