1. Reworked the xmlDocToJSON and _xmlDocToJSON functions for clarity.

1. Reworked the xmlDocToJSON and _xmlDocToJSON functions for clarity.
In particular: _xmlDocToJSON() now returns void, and requires its
second parameter (the jsonObject*) to be non-NULL.  The old version
behaved differently depending on whether the second parameter was NULL.
I found that arrangement confusing.

2. Finished adding doxygen-style comments; removed comments from the
header so that they won't override the more complete comments in the
implementation file.

3. Tinkered with white space here and there.

M    include/opensrf/xml_utils.h
M    src/libopensrf/xml_utils.c

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@1928 9efc2488-bf62-4759-914b-345cdb29e865