Extend public functions

[cfr42]

fontinst.lua currently starts by copying

• os_newline_cp
• localtexmf()
• get_script_name()
• dep_install(deps)

Please would you consider making these available publicly?

I'd particularly like to have dep_install() and localtexmf() available so I'm not copying global functions. I can obviously use different names, but I'd prefer not to if there's no good reason.

[cfr42]

Also unpack() ...