sql.py: put_table(): Use new empty_temp()

import.stats.xls: Added comments for estimated numbers. Added "," separators to large numbers.

sql.py: empty_temp(): In debug_temp mode, leave temp tables there for debugging

sql.py: empty_temp(): Don't output at log_level 2 because it's an internal query, not part of the core algorithm

sql.py: truncate(): Added kw_args to pass to run_query()

Added inputs/import.stats.xls, which compares row-based and column-based import. This shows that column-based import is slowed down by table locking when run simultaneously, so we will need a new INSERT IGNORE replacement that doesn't lock tables.

inputs: Ignore OpenOffice.org lock files

sql.py: empty_temp(): Don't print log message if not emptying any tables

db_xml.py: put_table(): Empty unneeded temp tables to free up memory

sql.py: Added empty_temp()