[Libvir] [PATCH] Enhance virBuffer code

Apart from a couple of minor fixes, this adds the following useful functions to the virBuffer implementation: virBufferAddChar: Append a single character to the buffer. virBufferURIEncodeString: Append a %-encoded string to the buffer (eg. virBufferEscapeString and the similar function in libxml2). Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903