Initial commit of version scripts (#1033)

This PR drops in a copy of our usual version-bump scripts (previously
used in Pyk, currently in all semantics projects). We want this
versioning information to make CI improvements to K a bit more
ergonomic.

It explicitly does not run the scripts in CI yet, because we rely on
`package/version` existing in the PR base branch. I will follow this PR
up with a matching one that correctly bumps the version on PRs.

Author: Baltoli

package/version

@@ -0,0 +1 @@
+0.1.0

package/version.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+set -xeuo pipefail
+
+notif() { echo "== $@" >&2 ; }
+fatal() { echo "[FATAL] $@" ; exit 1 ; }
+
+version_file="package/version"
+
+version_bump() {
+    local version release_commit version_major version_minor version_patch new_version current_version current_version_major current_version_minor current_version_patch
+    version="$1" ; shift
+    version_major="$(echo ${version} | cut --delimiter '.' --field 1)"
+    version_minor="$(echo ${version} | cut --delimiter '.' --field 2)"
+    version_patch="$(echo ${version} | cut --delimiter '.' --field 3)"
+    current_version="$(cat ${version_file})"
+    current_version_major="$(echo ${current_version} | cut --delimiter '.' --field 1)"
+    current_version_minor="$(echo ${current_version} | cut --delimiter '.' --field 2)"
+    current_version_patch="$(echo ${current_version} | cut --delimiter '.' --field 3)"
+    new_version="${version}"
+    if [[ "${version_major}" == "${current_version_major}" ]] && [[ "${version_minor}" == "${current_version_minor}" ]]; then
+        new_version="${version_major}.${version_minor}.$((version_patch + 1))"
+    fi
+    echo "${new_version}" > "${version_file}"
+    notif "Version: ${new_version}"
+}
+
+version_sub() {
+    local version
+    version="$(cat $version_file)"
+}
+
+version_command="$1" ; shift
+
+case "${version_command}" in
+    bump) version_bump "$@"                      ;;
+    sub)  version_sub  "$@"                      ;;
+    *)    fatal "No command: ${version_command}" ;;
+esac