VS Code extension

[Igmat]

According to this survey editor called VS Code is the most popular choice in JS community.
I use it in day-to-day work also.

So improving developer experience with extension for baset seems to be reasonable. Also, because .md specs is one of the most important features (see #11, #14)m this plugin will provide a lot of stuff around it.

Features

1. There is no option to set a breakpoint in .md file by default, so this extension should provide debugger for this purposes;
2. Diff for .md files that shows differences in preview mode instead of text mode;
3. Intellisense in code blocks of .md files;
4. Code lens for tests and coverage;
5. Integration with baset workflow mode (Watch/Workflow mode #65) - every time developer switches to another source file (defined in files option of baset config), this extension should open preview of related .md spec/baseline;
6. Highlight recent changes in preview;
7. Optionally, if preview tab gets focus it should switch to edit mode;
8. Optionally, add some animation when something changes in preview, so developer will get more attention to things that have been changed;
9. Buttons and command for fast acceptance;
10. Some additional commands for automating of common testing stuff (e.g. initial setup, generating tasks/launch configs, etc.);
11. Syntax highlighting for .base extension format (nearly the same as .json);
12. JSON schema for .basetrc