A new era of oBIX client side APIs

This massive set of patches redo the client side API implementation,
basically to make it starting to be really usable for real production
in every respects.
Resurrect the hard copy of list.h from Linux kernel source tree

To avoid unnecessary dependency to linux-devel package which will
invite build issues on old 2.6.x kernel used by RHEL6, a hard copy
of <linux/list.h> and friends from the Linux kernel source tree is
included directly.
Remove the XPath predicate usage from batch.c

This is for performance improvement since the batchIn document
generally speaking won't be difficult to parse manually and also
XPath could not handle different namespace not registered earlier

Thanks Tyler!