added tab support to the terminal emulator

module/vt100.lua

@@ -31,6 +31,8 @@ function vt100emu(gpu) -- takes GPU component proxy *gpu* and returns a function
      cx = 1
     elseif cc == "\27" then -- escape
      mode = "e"
+    elseif cc == "\t" then
+     cx = 8*((cx+9)//8)
     elseif string.byte(cc) > 31 and string.byte(cc) < 127 then -- printable, I guess
      gpu.set(cx, cy, cc)
      cx = cx + 1