Removed 'jerry_parse_and_save_literals' and introduced
'jerry_get_literals_from_snapshot' instead which works
on snapshot buffers rather than source code. Added literal
saving feature to snapshot merge in the snapshot command
line tool. Also added missing 'jerry_cleanup()' calls to the
snapshot tool. Improved the console messages of the snapshot
tool.

Based on previous work of Tamas Zakor <ztamas@inf.u-szeged.hu>

JerryScript-DCO-1.0-Signed-off-by: László Langó llango.u-szeged@partner.samsung.com