* improve performance of sample_neighbors
* some more improve
* test script
* benchmarks
* multi process
* update more tests
* WIP
* adding two API for state saving
* add create from state
* upd test
* missing file
* wip: pickle/unpickle
* more c apis
* find the problem of empty data array
* add null array; pickling speed is bad
* still bad perf
* still bad perf
* wip
* fix the pickle speed test; now everything looks good
* minor fix
* bugfix
* some lint fix
* address comments
* more fix
* fix lint
* add utest for random.choice
* add utest for dgl.rand_graph
* fix cpp utests
* try fix ci
* fix bug in TF backend
* upd choice docstring
* address comments
* upd
* try fix compile
* add comment
* trying to refactor IndexSelect
* partial implementation
* add index select and assign for floats as well
* move to random choice source
* more updates
* fixes
* fixes
* more fixes
* adding python impl
* fixes
* unit test
* lint
* lint x2
* lint x3
* update metapath2vec
* debugging performance
* still debugging for performance
* tuning
* switching to succvec
* redo
* revert non-uniform sampler to use vector
* still not fast
* why does this crash with OpenMP???
* because there was a data race!!!
* add documentations and remove assign op
* lint
* lint x2
* lol what have i done
* lint x3
* fix and disable gpu testing
* bugfix
* generic random walk
* reorg the random walk source code
* Update randomwalks.h
* Update randomwalks_cpu.cc
* rename file
* move internal function to anonymous ns
* reorg & docstrings
* constant restart probability
* docstring fix
* more commit
* random walk with restart, tested
* some fixes
* switch to using NDArray for choice
* massive fix & docstring
* lint x?
* lint x??
* fix
* export symbols
* skip gpu test
* addresses comments
* replaces another VecToIdArray
* add randomwalks.h to include
* replace void * with template
* rng refactor
* fix bugs
* unit test
* remove setsize
* lint
* fix test
* use explicit instantiation instead of inlining
* stricter test
* use tvm solution
* moved python interface to dgl.random
* lint
* address comments
* make getthreadid an inline function
Qidong Su