enhance software configuration

• enable use of HTTP/HTTPS protocol as an alternative way of loading files when FTP does not work
• enable to override KL_WORKING_DIR, KL_CONF_DIR, KL_LOG_XXX and KL_DEBUG variables before calling command-line scripts using environment variables
• enable to override conf/dbms.conf properties using environment variables, too. For this feature to work on the command line, replace '.' separator of variable names by '__' (double underscore); e.g. to override 'mirror.path' variable definition (as usually defined in conf/dbms.conf file), do this on bash shell: export KL_mirror__path="/path/to/banks".
• new Singularity recipe with a fully autonomous software; no need anymore of setting up an external conf directory