Add -a Option to list.lua

[Wilma456]

This PR simple adds a -a Option to list.lua which allows you to see hidden Files, even if the list.show_hidden setting is false.

[KnightMiner]

This is minor, but bShowHiddenOption should be before the string.sub as it's the faster condition (shortcircuiting will mean we never need the strong.sub call then)

[SquidDev]

I feel it'd be good to support ls foo -a as well. Maybe do something like

local sDir = shell.dir()
local bShowHiddenOption = false
for i = 1, #tArgs do
  if tArgs[i] == "-a" then
    bShowHiddenOption = true
  else
    sDir = tArgs[i]
  end
end

[dmarcuse]

What happens if you want to list files in the -a directory? You'd have to do ls -a -a for it to work, which would also show hidden files when you might not want them, or cd -a and then ls, which adds an extra command.

[SquidDev]

@apemanzilla I believe you can just do ls ./-a then: that's what one does on Linux at least.

[thatcraniumguy]

Can one of the admins verify this patch?