bitproto v1.2.0

Changes:

• LSP Server: Add a simple bitproto-language-server, tested on neovim and vscode.
• VsCode Extension: Upgraded to support bitproto-language-server (v1.2.0)

Upgraded:

• bitproto compiler → v1.2.0 (to support lsp feature)
• bitproto-language-server → v1.2.2 (https://pypi.org/project/bitproto-language-server/)
• vscode extension → v1.2.0 (https://marketplace.visualstudio.com/items?itemName=hit9.bitproto)

No changes for C/Python/Go lib.

How to Install:

• https://github.com/hit9/bitproto/tree/master/editors/language_server
• Vscode: https://github.com/hit9/bitproto/tree/master/editors/vscode/bitproto