* switch eager mode and change it

* set default is eager

* set default is eager

* fix error; test=develop

* fix some error; test=develop

* update

* upd

* update code; test=develop

* update

* fix some bug; test=develop

* fix bug; test=develop

* fix bug; test=develop

* fix bug; test=develop

* fix error; test=develop

* format; test=develop
Co-authored-by: NJiabinYang <360788950@qq.com>

* add beta distribution
* add kl_divergence and register_kl api

* extend Distribution baseclass for supporting multivariant distribution and prob method

* add ExponentialFamily base class and entropy using Bregman divergence

* add dirichlet probability distribution