re-enable conda builds

only build for most recent python version

fix bug in split/cv

Fix a bug in estimate command. Thanks to @leopeidel for pointing out …

…the bug.

bugfixes and updates.

Add options to bound Ne

bug fixes and performance improvments. by popular demand, default fit is

now piecewise like [PM]SMC.

fix build process

merge devel branch.

Recode monomorphic sites instead of exiting