Net-Z3950-ZOOM

Changes for version 1.01

Place some CODE: chunks in "ZOOM.xs" inside curly brackets so that the declarations they begin with are at the start of the block. This avoid mixed code/declarations. (The "correct" solution is to use INIT: clauses in the XS file, but they don't seem to work: the code in them is slapped down right next to the CODE:, so declarations are not acceptable there either.)
Add new function Net::Z3950::ZOOM::connection_scan1(), which uses a query object to indicate the start-term. This opens the way for using CQL queries for scanning once the underlying ZOOM-C code supports this.
NOTE BACKWARDS-INCOMPATIBLE CHANGE: The ZOOM::Connection method scan() is renamed scan_pqf(), and a new scan() method is introduced which calls the underlying scan1() function. Thus the scan()/scan_pqf() dichotomy is consistent with that between search()/search_pqf().
The tests t/15-scan.t and t/25-scan.t now also test for scanning by CQL query. To support these tests, a new files is added to the distribution, "samples/cql/pqf.properties"
Remove nonsensical clause about CQL sort-specifications from the documentation.
Add new function Net::Z3950::ZOOM::query_cql2rpn(), for client-side CQL compilation.
Add new ZOOM::Query::CQL2RPN class, encapsulating CQL compiler functionality as a Query subclass.
Add two new error-codes, CQL_PARSE and CQL_TRANSFORM, returned by the client-side CQL facilities.
The test-scripts t/12-query.t and t/22-query.t are extended to also test client-side CQL compilation.
Add all the yaz_log*() functions within the Net::Z3950::ZOOM namespace.
Add new ZOOM::Log class for logging, providing aliases for the functions in the Net::Z3950::ZOOM layer.
Add diagnostic set to rendering of Exception objects.
Documentation added for CQL compilation and logging.