altname is dropped during summarise_motif

[Spencer Nystrom]

although as.data.frame behaves correctly, summarise_motifs always drops the 'altname' column.

m <- create_motif()

m["altname"] <- "myAlt"
m["organism"] <- "drosophila"
m["family"] <- "ETS"

df <- universalmotif::as.data.frame(m)
summary <- universalmotif::summarise_motifs(m, na.rm = F)
df$altname == summary$altname

This is caused by a typo in summarise_motifs_cpp.