Created by: zhiqiu

PR types

Function optimization

PR changes

APIs

Describe

Refine paddle.manual_seed()

• use default generator to control random number generation
• return default generator
• update doc
• update 70+ unittests that use random_seed, replaces program.random_seed=seed with paddle.manual_seed(seed) in several unittests.

NOTE, Currently there are 2 conditions of random number generation for users: (1) op seed is not set, use default CPU Generator (2) op seed is set, use a unique random engine for each and set the seed as op seed