some fixes, cleanups, and updates, plus a new instant-block feature for root login attempts

Here are some changes that might be interesting and/or useful.

• a useful common pidfile default value

• add emacs mode line

• fix the ipfilter backend to be dynamic

• immediately block sources of "root" login attempts

• logging tweaks

• hints about how to build from source

• various related fixes and improvements:

  • remove AM_PROG_AR -- not needed, not supported by some automake macros

  • reinstate --with-firewall -- a config file must be optional!

  • add --with-rst2man to support alternate tools

  • remove the "kill -PIPE" nonsense -- if your system doesn't do this properly then it is not POSIX compatible and you have much bigger problems to worry about!

  • support options for alternate internal filters for testing

  • don't ever run 'cat' for nothing!

  • update some documentation

• hmmm... 'git mv' had no lasting effect?

• mention ipfilter and re-justify