Figure S3 formatting

[ewallace]

Clear up formatting of Supplementary Figure S3. (histogram of Relative positions of TGTAHMNUA and HWNCAUUWY motifs in native 3’UTRs.)

• use the same theme, modified theme_cowplot as in shared_figure_formatting.R
• expand limits less, I think xlim = c(0,1)?
• Give additional line of explanation. Maybe "Histogram shows the counts of the motif occurrences in 3'UTRs relative to the total length of 3'UTR, where 0 would be starting exactly at the stop codon and 1 would be at the reported poly(A)-site. See (methods or ref to data repository) for details."

[DimmestP]

Fixed with commit 3307d34710ecc2488f26e8fc664d67c637889df5