Fix: refactor profiling IDs from statics to state members

[ggcrunchy]

As mentioned in the closing comment of #660, I realized the case with static IDs was pretty hopeless. Thankfully, it was actually rather easy at this point to move them into the ProfilingState, which was on hand when they were needed. Previous design was a bit of inertia from the former stack trace-stifling version. 😄

I reproduced the issue on Mac, mentioned in #help-and-support on Discord, where launching from, say, the file dialog, would lead to a crash. With this it goes away.

[ggcrunchy]

I let leak slip into the PR commit (details in 894b3ad's comments). That should be fixed now; I let this test churn through a few million objects and memory leveled off early and held steady:

local ii=0
local jj=0
local kk=0

Runtime:addEventListener("enterFrame", function()
  ii=ii+1
  for _ = 1, 50 do
    local r = display.newRect(1, 2, 3, 4)
    r:addEventListener("buffalo", function()
      jj=jj+1
    end)
    function r.cow ()
      kk=kk-2
    end
    r:addEventListener("cow")
    r:dispatchEvent{ name = "buffalo" }
    r:dispatchEvent{ name = "cow" }
    r:removeSelf()
  end
  if ii == 500 then
    print("!!", jj, kk)
    ii=0
  end
end)

I did a bit of reorganization while I was at it. I'm double-checking with those folks that I know did anything with the results so far, but made a very slight change to the output of display.getTiming(): when time is false, if the what string starts with @ it's a "keyword" (so far either "@tableListeners" or "@functionListeners"). My "basic example" in #551 then has the following change:

local function PrintList (name, indent)
  local timings = table.remove(tstack) or {}
  local n = display.getTimings(timings, name)

  indent = indent or " "

  print(indent .. "> " .. name)

  for i = 1, n, 2 do
    local what, time = timings[i], timings[i + 1]

    if time then
      print(indent .. " ", what, time / 1e3)
    elseif what:starts("@") then -- keyword?
      if what:ends("Listeners") then
        print(indent .. "  *" .. what:sub(2))
      end
    else -- sublist?
      PrintList(what, indent .. "  ")
    end
  end

  tstack[#tstack + 1] = timings
end

[ggcrunchy]

849f318's comment should read "assumption of aligned strings". Anyhow, with that revision it seems okay on Mac, and I'll put it through its Android paces shortly.