Explain better the potential value order
Install hcli to the bin directory
Update the usage string for hcli
PFL manual: add section for horus cli
PFL manual: improve title page and reword a sentence
PFL manual: use the Unix end-of-line marker
Add support for more infernce keys.

Add support for export_libdai, export_uai, export_gv and print_fg.
Document these keys.