add shot numbers in legend automatically with doplot=-1

inor bug fix in gdat_tcv and gdat_plot as well

add cell array in 2nd cell for expression argument

used mex path to get ids_gen so has int32 and '' for empty strings

add trialindx when non empty for generic calls, to tcv2ids and fix legend in TCV/CXRS_get_profiles.m

for ids as well, at this stage dealt with before output of gdat_tcv for each case with single function gdat2time_out.m