Use Github Actions instead of Travis

Moved MSVC to Github Actions as well.

.ci/linux-fresh/docker.sh

@@ -0,0 +1,5 @@
+#!/bin/bash -ex
+
+mkdir build && cd build
+cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=/usr/lib/ccache/gcc -DCMAKE_CXX_COMPILER=/usr/lib/ccache/g++
+ninja

.ci/linux-fresh/upload.sh

@@ -0,0 +1,12 @@
+#!/bin/bash -ex
+
+. .ci/common/pre-upload.sh
+
+REV_NAME="threeSD-linux-${GITNAME}"
+
+mkdir "$REV_NAME"
+cp build/bin/threeSD "$REV_NAME"
+
+mkdir "$REV_NAME/dist"
+
+. .ci/common/post-upload.sh