Travis CI improvements:

FIXES: #2527

* define custom docker image for travis-linux builds based on
  package build image
* add macos builds
* add windows builds (currently allowed to fail)
* improve build and shell scripts as required for the CI envs
* add asio timer latency workaround
* omit several manual tests from TravisCI which cause memory exhaustion

bin/ci/ubuntu/build-in-docker.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+# run our build script in a docker container
+# using travis-ci hosts
+set -eux
+
+function join_by { local IFS="$1"; shift; echo "$*"; }
+
+set +x
+echo "VERBOSE_BUILD=true" > /tmp/co.env
+matchers=(
+   'TRAVIS.*' 'CI' 'CC' 'CXX'
+   'BUILD_TYPE' 'TARGET' 'MAX_TIME'
+   'CODECOV.+' 'CMAKE.*' '.+_TESTS'
+   '.+_OPTIONS' 'NINJA.*' 'NUM_.+'
+   'NIH_.+' 'BOOST.*' '.*CCACHE.*')
+
+matchstring=$(join_by '|' "${matchers[@]}")
+echo "MATCHSTRING IS:: $matchstring"
+env | grep -E "^(${matchstring})=" >> /tmp/co.env
+set -x
+# need to eliminate TRAVIS_CMD...don't want to pass it to the container
+cat /tmp/co.env | grep -v TRAVIS_CMD > /tmp/co.env.2
+mv /tmp/co.env.2 /tmp/co.env
+cat /tmp/co.env
+mkdir -p -m 0777 ${TRAVIS_BUILD_DIR}/cores
+echo "${TRAVIS_BUILD_DIR}/cores/%e.%p" | sudo tee /proc/sys/kernel/core_pattern
+docker run \
+    -t --env-file /tmp/co.env \
+    -v ${TRAVIS_HOME}:${TRAVIS_HOME} \
+    -w ${TRAVIS_BUILD_DIR} \
+    --cap-add SYS_PTRACE \
+    --ulimit "core=-1" \
+    $DOCKER_IMAGE \
+    /bin/bash -c 'if [[ $CC =~ ([[:alpha:]]+)-([[:digit:].]+) ]] ; then sudo update-alternatives --set ${BASH_REMATCH[1]} /usr/bin/$CC; fi; bin/ci/ubuntu/build-and-test.sh'
+
+