Indira protocol format changed a little.

Now "foo bar=baz" must have a word at the beginning and is transported as
a tuple {first_word, [rest, {stuff, V}]}.
Added stub for new public function.
Implemented writing pidfile.
Added TODO entry in indira module.
Exported indira:load_app_config/1.
Replaced all io:fwrite() calls with error_logger.

Now this finally starts to look like a framework.
Allowed just a keyword command in Indira protocol.
Rephrased indira:command() description.
Added skeleton for Indira's error handlers.
Implemented basic STDOUT log handler.
Designed options for indira:setup_logging().

The function is not implemented yet, though.
Added some comments, including TODO in doc.
Fixed indira:start_rec/2: it was incorrectly calling start_rec/1.
Added assertion to indira:write_pidfile().

indira:chdir() already has one. Let's make all the functions similar.