Added missing space before exit code.

Check if directory for LOCKFILE is writable.

Remove home path from config.sh.example

fixed whitespace-stripping, replace all whitespace in domains.txt entries with single space character (fixes #60 and #78)

add support for dns-01 challenge - try 2

removed get_json_array helper, rearranged sign_domain method a bit, made grep for PEM-format-check quiet

rewritten command_revoke method (shortened + changed output to look less like one of those weird openssl error messages)

rewritten argument handling and moved to new main() method, added dependency checks, added _exiterr helper

Changed shebang of import-certs.sh to #!/usr/bin/env bash