Incorporate selfing about dadi HOT 2 OPEN

There are two potential issues.
1) Selfing may affect the variance effective population size, changing the 
interpretation of Ne results. More 
problematic, it might also change conversion of genetic units to physical 
units, since those are all in terms of 
Ne.
2) If the individuals sampled are not outbred, the frequency spectrum would be 
substantially distorted. For 
example, if all the sampled individuals were the direct result of 
self-fertilization, the number of singletons will 
be dramatically depressed.

In regards to 1), Crow and Denniston (1988) _Evolution_ 42:482 suggests that 
selfing should *not change* the 
variance effective population size. (Comment after Eq. 19.)