Add test of calc_genoprob for f2 X chr; fix bug for that case
Add test of calc_genoprob for bc X chr
Add test of calc_genoprob for f2 X chr with one sex/direction
Add test of calc_genoprob for bc X chr with one sex
Remove a bunch of library(qtl) from tests
Add tests of est_map for X chr in bc/f2
Trying to fix up est_map to handle the general case

 - noticed a serious problem: can't just take proportion of recombinants
   as the estimate of the recombination fraction; for RIL, need to
   back-transform using relationship between rf at meiosis and frequency
   of exchanges on RI chromosome

 - summed gamma values across individuals and plugged in an est_rec_frac
   function, but I'm not sure that this will work in the general
   case (e.g., CC or DO)