makefile: Added the "test" rule
To keep valgrind happy: free all malloc()ed memory at the end
pbwtMerge: Merge only records present in all files (intersection, not a union); Handle duplicate positions (for now assuming that records are sorted by the REF+ALT string)
Merge remote branch 'remotes/rd/master'
pbwtMerge: resolved merge conflict, renamed old "Update" struct to the new "PbwtCursor"
Merge pull request #2 from pd3/master

Changes in pbwtMerge - I hope it now compiles at least!