* [TENSORFLOW] Convert scalar Const into tvm.relay.const

* use _get_num_param() and _get_list_param()

* Add gradient implementations

* Add docstrings to fix lint errors

* test_darkent_bug

* test_darkent

* add resnext tests

* [VTA][Chisel] add scalafmt and format existing scala codebase

* change column width to 100

* add scalafmt conf file as a valid file type

* add asf header to scalafmt conf file and rerun formatter

* [VTA] Fix TSIM compile error in Linux (add missing -fPIC flag);

* [VTA] Fix TSIM compile error in Linux (add missing -fPIC flag);

* fix indentation problem;

This reverts commit 224cc243.

As GraphRuntime does not provide control-flow logics, we have to split
our model to two parts. While we need to share parameters between them
to save memory usage.

Solution:
1) add "lazy_init_input" in graph's attributes
   "attrs": {
     ... ...
     "lazy_init_input": [
       "list_str",
       [
         "p0"
       ]
     ]
    }
2) allow un-allocated NDArray entry in SetupStorage
3) utilize "set_input_zero_copy" function to set parameters

* fix

* lint

* init shape func in interpreter and vm compiler

* Update interpreter

* fix

* lint

* lint

* fix

* remove hack

* update

* fix

* fix

* update

* address comments & update for shape_of

* fix lint

* update

* fix hybrid

* lint

* fix bug & add take shape func

* lint

* lint

* update

* fix flaky test

* add todo

* Added arm_cpu NHWC schedules.

* Fixed kernel shape legalization.

* Added bitserial ops to relay.

* Snapshot and more missing files.

* Added dense testing.

* Added tests

* Added ASF header to new files.

* cc lint

* Pylint change.

* pylint fixes.

* Change arm legalize test.

* Added assert check to arm legalize.

* Added better documentation, fixed some bad style

* Reverted arm conv2d nhwc changes.

* [VTA][TSIM] add virtual memory support to tsim example

* fix identation

* remove USE_TSIM macro and use 32-bit addr instead

Issue
when try vta on fpga board, would see a Infinite recursive
device_api.ext_dev issue that cause stack overflow and vta
failed.

Analysis:
device_api.ext_dev function in rpc_server.py is use to load
vta library, once vta library get load, device_api.ext_dev would
get replaced with vta function by vta library, vta device_api.cc
did such work, but because a logic issue in VTA.cmake, the said file
not get compiled, then vta would keep failing on rpc_server.py.

Solution:
fix the logic issue in VTA.cmake.

Issue:
RewriteForceSerial is a debug function to force instructions
to be serialize instead of parrallel running, by doing so we
can isolate some parallel problem or do performance compare
between parallel and serialize. But this function have some
problem, once get enabled by set debug flag, vta would stuck
when running on pynq board.

Analysis:
once enable RewriteForceSerial, the dependency logic is different
with default one, but we still use same logic to generate FINISH
and other logic, this would cause dead lock.

Solution:
give a different dependency settings when enable RewriteForceSerial.

* [Relay] Conv2d grad

* Fix test

* Fix first order gradient

* Not assuming HOME in tvm/download.py

* Trigger notification

* [TensorFlow] Fix limitation that depth_mult can only be 1 for DepthwiseConv2dNative

* Improve code readability

* [AutoTVM] Fix database APIs

* Refactor the byte conversion

* [Relay][Keras] Dot

* fix reshape

* fix comments

* fix inconsistent python/cpp APIs for if_then_else

* fix error message

* fix power consistency

* fix

* fix bug

* add test