Add bridge ortholog mapping

[ivokwee]

Add bridge orthology search for poorly annotated species. Bridge orthology search uses an intermediate species (BRIDGE_SPECIES = dmelanogaster, drerio, celegans, scerevisiae, athalian) to map an organism first, then using the bridge species maps to human orthology next. This can improve orthology mapping for poorly annotated species (like Fall armyworm). Better orthology mapping is useful for geneset analysis, drug connectivity and experiment similarity in OPG.

[ESCRI11]

current state of PR does not even parse

Error in FUN(X[[i]], ...) : 
  /playbase/R/pgx-annot.R:1443:1: unexpected '}'
1442:   return(top_match)
1443: }
      ^

please fix before i can try to run it and review

[ivokwee]

@ESCRI11 ok. try again.