TAQsymbols only, for back forth of ticker per 1 permno, seems not affected

Signed-off-by: Oleg Komarov <o.komarov11@imperial.ac.uk>
taq2cusips: back and forth changes in ticker (same cusip) with correct date

Signed-off-by: Oleg Komarov <o.komarov11@imperial.ac.uk>