The print nodes option can now accept an optional field list to
customise the output. This is ugly, since the field names do not match
the header names, but it is at least barely customisable (at runtime).

Also fixes some other small issues in man pages.

The strange printf usage is due to some limitation (it seems) in ghc for
very long argument lists. The whole printout should be rewritten later.

This is useful especially for hspace, where we might want to simulate a
hypothetical cluster to check allocation beforehand.

This patch beautifies the man pages for hbal and hspace.

This (big) patch changes the output of hspace from text-format
(separated by ‘: ’) to a shell-snippet, in ‘key=value’ format.

This will allow sourcing the output or parsing it via awk/sed/etc.