use different sed version for different system types (mostly for compatibility with ancient linux distros nobody should be using anyway ¯\_(ツ)_/¯)

Require $WELLKNOWN only when using http-01.

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)