started implementation of class for sum status
Merge branch 'master' into modular_summary_statistics
add infrastructure for summary statistics
centralize Makefile

to make management of src files less painful
porting segregation sites to new sum stat system
reset seg sites after each locus
port site frequency spectrum to new system
port tree printing to new sumstat system
Merge branch 'master' into jz
when scrm is directly called, simulate segregating sites