The Histogram Constructor have allocated memory for storing
the variable vector<int> frequency, but not release after then.
I have created a destructor function to free the memory.

Add usage manual for VisualDL, and modify four pictures in directory demo/component/usage_interface. (#549)

The usage maunal will be helpful for beginners to make use of VisualDL.

The components of ViusalDL are introduced in details,
including definitions of functions, parameters explanations.
Moreover, demos are given for each component.

The former pictures of demo are lack of some details in the frontend webpage,
I upload new pictures to make demo more intuitive.

add component usage demo

* update README

* release 1.3.0

* update README

* sync

* sync

* sync

* sync

* only support Float32

* add more data types

* clang format

* clang format

* typo fix in vdljl.cc

* Delete vdl.jl

Git tag 9f69353562fe is the last commit in protobuf 3.1.x.

* Update the travis script

* update doc generate path

* revert test

* test

* test

* test

* test

* test

* Update script

* Pull from PPO develop branch to test

* Remove tmp print messages

* We don't need no, PYTHONIFICATION

* Fill small shell typo

* add paddle framework.proto and support show paddle-fluid model in web page

* modify the graph drawing policy, only draw operator node in default

* Resolution of code style issues raised by Superjomn

* front-end add vue-i18n dependency

* back-end support language selection with option --language or -L

* front-end add language support with vue-i18n

* Runs state should be reflected when query changes caused by back navigation

* Maintain run state after refresh

* finalized global run selector UI

* Add runs selector open UI effect

* Add back release history

* fix format

* New menu json

* Updated menu.json

* prepare for v1.1 release

* upload missing onnx model

* Add install by sources section and a link to dev server

* Update VisualDL logo

* Add preliminary support for Windows

    Known issues:

    1. No zlib support for protobuf
    2. Manual editting to core.vcxproj are required
    3. No build and packge script support
    4. Not tesetd, may break linux build

* Add build script and batch file for Windows

* Fix linux build and include batch file in wheel

* Fix Python 2.7 build

* Define NOMINMAX instead of preventing macro expansion

Downgrade the Sphinx to use 1.5.6