csv -> sql loaders
into csv sqlite test
add into/append to datashape.namespace
add drop functions to backends (untested)
add drop file
list of lists to numpy recarray
various small fixes
discover row proxy
iterator -> chunks reifies first chunk

This helps to identify errors immediately
handle subclasses of iterator, np.ndarray
convert(set, ...) turns unhashable iterables into tuples
csv supports kwargs
sql resource creates database if necessary
avoid dynd route by bumping numpy cost
discover csv headers stripped of white space
fix postgres copy command
write csv header by default
recost dynd to avoid it for now
list/set functions avoid non-iterables

This is to avoid list-of-lists and list-of-sqlalchemy.RowProxys
only pass on NotImplementedErrors, not all exceptions