ensure probe_strand value is updated to reflect strand inversions

[conorcamplisson]

RNA probes are obtained by intersecting (+) strand DNA probes with exon annotations, and inverting probe strand as needed to handle +/- strand annotations, i.e. for (+) strand annotations, the (+) strand DNA probe sequences are reverse complemented to obtain the corresponding RNA-binding probe sequences. However, it appears that while probe sequences are correctly reverse complemented as needed, the value of the probe_strand field is not updated to (-) as it should be to reflect the strand inversion.

Additional details: beliveau-lab/PaintSHOP_resources#2