Summary:
this moves sandbox/grist to core, and adds a requirements.txt
file for reconstructing the content of sandbox/thirdparty.
Test Plan:
existing tests pass.
Tested core functionality manually. Tested docker build manually.
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2563
The cssVars.ts file has changed to include some more knobs
for custom theming. This commit updates the file, and
introduces a `stubs` directory for stubbing code that is
specific to our deployments of Grist and not of general interest.
