catgirl 2.1

Now featuring separate input buffers for each window! Windows with
pending input appear in the status line with an '@' symbol, which
is documented in the new INTERFACE section of the manual along with
explanations of the rest of the interface. Pending input is also
saved in the save option file.

This release also adds C-z s and M-s bindings to set spoiler text
and temporarily reveal spoiler text, respectively. catgirl will now
prompt for server or SASL passwords at startup if the corresponding
configuration option is left blank (e.g. "sasl-plain = user:").

Word-based line editing functions now treat any amount of whitespace
and punctuation as word boundaries. Formatting in the input line
no longer changes when moving the cursor across formatting codes.

The build instructions for the sandman tool have changed.