Merge pull request #6999 from ethereum/develop

Merge develop into release for 0.5.10

Author: chriseth

.circleci/README.md

@@ -0,0 +1,21 @@
+## CircleCI integration
+
+### Docker images
+
+The docker images are build locally on the developer machine:
+
+```!sh
+cd .circleci/docker/
+
+docker build -t ethereum/solc-buildpack-deps:ubuntu1904 -f Dockerfile.ubuntu1904 .
+docker push solidity/solc-buildpack-deps:ubuntu1904
+
+docker build -t ethereum/solc-buildpack-deps:archlinux -f Dockerfile.archlinux .
+docker push solidity/solc-buildpack-deps:archlinux
+```
+
+which you can find on Dockerhub after the push at:
+
+    https://hub.docker.com/r/ethereum/solidity-buildpack-deps
+
+where the image tag reflects the target OS to build Solidity and run its test on.