Add missing perl and ps dependencies and remove bash (because Essential
packages are not supposed to be there).

Switch to packaging model where each module goes into separate package.

Such model makes much more sense (after all it's also how big platforms
such as python do it).  It allows better control over dependencies and
allows re-locating modules properly according to compatibility level
(i.e. now exit.sh can go to 'sh' despite the fact that in 'core' it had
to be with other Bash-compatible modules).

Also a first POSIX-oriented library!

Used to declare POSIX orientation (in terms od Shellfu), plus to hold
'include-sh' directory on RPM-based distributions.

Turns out that since shellfu-doc uses pretty.sh (and makes good use of
it), what we had was broken cyclic dependency.

shellfu-doc and shellfu-embed are useful mostly for developers, though,
so it's no shame to split them.

Mostly ugly (at least how lintian sees it) but first working version.