added papermc, waterfall and a small script update

siverten/waterfall/Dockerfile

@@ -0,0 +1,35 @@
+ARG WATERFALL_VERSION=latest
+ARG JAVA_VERSION=11
+
+FROM alpine AS tools
+RUN apk add --update-cache --no-cache \
+        curl \
+        jq
+
+FROM tools AS waterfall
+RUN if test -z "${WATERFALL_VERSION}" || test "${WATERFALL_VERSION}" == "latest" || test "${WATERFALL_VERSION}" == "master"; then \
+        echo "### Fetching latest version"; \
+        WATERFALL_VERSION=$(\
+            curl --silent --location https://papermc.io/api/v1/waterfall/ | \
+            jq --raw-output '.versions[0]' \
+        ); \
+    fi && \
+    echo "### Using version <${WATERFALL_VERSION}>" && \
+    WATERFALL_VERSION_PATCH=$(\
+        curl --silent --location https://papermc.io/api/v1/waterfall/${WATERFALL_VERSION}/ | \
+        jq --raw-output '.builds.latest' \
+    ) && \
+    echo "### Using patch <${WATERFALL_VERSION_PATCH}>" && \
+    curl --silent --location --fail --output /waterfall.jar https://papermc.io/api/v1/waterfall/${WATERFALL_VERSION}/${WATERFALL_VERSION_PATCH}/download
+
+FROM openjdk:${JAVA_VERSION}-jre
+RUN useradd --create-home --shell /bin/bash minecraft \
+ && mkdir -p /opt/waterfall /waterfall \
+ && chown -R minecraft /waterfall/
+COPY --from=waterfall /waterfall.jar /opt/waterfall/
+USER minecraft
+WORKDIR /waterfall
+VOLUME /waterfall
+EXPOSE 25565
+ENV JAVA_MEM=1G
+CMD java -Xms${JAVA_MEM} -Xmx${JAVA_MEM} -jar /opt/waterfall/waterfall.jar