Parser.py: Renamed SyntaxException to SyntaxError because it's an unexpected condition that should exit the program, a.k.a. an error

bin/map: process_rows(): When iterating over each row, only retrieve the next row if the end (limit of # of rows) has not been reached. This prevents the next row from being fetched, possibly causing an entire additional consecutive XML document to be parsed, if the limit has already been reached. This is primarily useful for XML inputs with a ".0.top" segment prepended before the other documents, which contains just the first two nodes for fast parsing of this smaller XML document when only the first two nodes are needed for testing. Without this fix, the ".0.top" segment would have needed to contain the first three nodes instead.

inputs/XAL: Accepted initial test outputs

inputs/XAL: Added maps

bin/map: Extended consecutive XML document support to direct-XML inputs (without a map spreadsheet). Factored out consecutive XML document row-iteration code into helper method get_rows() which does the iters.flatten() and itertools.imap() calls.

bin/map: Fixed bug in iteration over consecutive XML documents where only the first element of the first document was processed. Use of iters.flatten() and itertools.imap() fixes this problem so that the consecutive XML documents are regarded as a continuous stream of rows.

bin/map: Use new xml_parse.docs_iter() to iterate over each consecutive XML document in stdin

xml_parse.py: Added support for parsing consecutive XML documents in a stream

Added iters.py

streams.py: Added FilterStream. Changed TracedStream to use FilterStream.