Improved environment setup

• Nice singularity prompt
• Use ls colors
• More transparent environment setup (copy scripts instead of writing them in the Dockerfile)
• Double-check all still works

containers/jug/profile.d/a00_cleanup.sh

+#!/bin/bash
+
+## Force environment to be clean
+export LD_LIBRARY_PATH="/lib/x86_64-linux-gnu:/usr/local/lib64:/usr/local/lib"
+export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+[ ! -z "$CC" ] && unset CC
+[ ! -z "$CXX" ] && unset CXX
+[ ! -z "$JUPYTER_CONFIG_DIR" ] && unset JUPYTER_CONFIG_DIR
+[ ! -z "$JUPYTER_PATH" ] && unset JUPYTER_PATH
+[ ! -z "$CLING_STANDARD_PCH" ] && unset CLING_STANDARD_PCH
+[ ! -z "$USER_PATH" ] && unset USER_PATH
+[ ! -z "$SHLIB_PATH" ] && unset SHLIB_PATH
+[ ! -z "$LIBPATH" ] && unset $LIBPATH
+[ ! -z "$CMAKE_PREFIX_PATH" ] && unset CMAKE_PREFIX_PATH
+[ ! -z "$SOFTWARE_HOME" ] && unset SOFTWARE_HOME
+[ ! -z "$ROOTSYS" ] && unset ROOTSYS