* [CODEGEN/PASS] Improve callpacked lowering, allow pass array callback.

* fix cython

* [LANG] CommReducer

* Reorganize c_api

* Remove InitValue and Combine; refactor Functor

* Make CommReducer an Expr

* Make comm_reducer type independent

* Make CommReducerNode a Node

* Small fix

* Refine

* Refine front api; add integration testcases for min/max

* Fix python

* Refine

* Fix lint and add example

* [DOC] Scan tutorial

* Fix according to ziheng's comment

* [SCHEDULE] Add group, refactor thread bind api.

* fix doc

* fix g++-4.8

* More testscase

* Remove graph context from fix pt analysis

* [LANG/GPU] Cross Thread Reduction.

* Fix doxygen error

* Upgrade verilog testcase to new one

* [RUNTIME] Refactor runtime to be DLPack compatible. Enable plugin of new runtime.

* fix mac compile

* ok

* [OP/LANG] Support Extern Call, more regression tests

* [TEST] Include pylintrc

* [IterVar/REFACTOR] Add types to IterVar

* [ARITH/REFACTOR] Move IntSet to include

* [REFACTOR/OP] Move Op detail to seperate folder.

* fix test