When adding elements to a table, the .add() function does not behave as
expected in various cases, making it really shit and difficult to use.
Instead, we keep our own index and just add one by one. It works, and
it's easy to understand.
This may lead to indices which are nil, i.e. non-fully-sequential
tables, but I can't be asked to worry about it because that shouldn't be
an issue when we use .set() everywhere.
Adds `Util.DebugExecutionTime()`, which returns a table of
`function_name: milliseconds`, in which each function's execution time
is averaged over all time.
You can call this function like so:
```lua
-- event to print the debug times
MP.RegisterEvent("printStuff", "printStuff")
-- prints the execution time of all event handlers
function printStuff()
print(Util.DebugExecutionTime())
end
-- run every 5 seconds (or 10, or 60, whatever makes sense for you
MP.CreateEventTimer("printStuff", 5000)
```
Pretty print function:
```lua
function printDebugExecutionTime()
local stats = Util.DebugExecutionTime()
local pretty = "DebugExecutionTime:\n"
local longest = 0
for name, t in pairs(stats) do
if #name > longest then
longest = #name
end
end
for name, t in pairs(stats) do
pretty = pretty .. string.format("%" .. longest + 1 .. "s: %12f +/- %12f (min: %12f, max: %12f) (called %d time(s))\n", name, t.mean, t.stdev, t.min, t.max, t.n)
end
print(pretty)
end
```
`Util.DebugExecutionTime()` returns a table, where each key is an event
handler function name, and each value is a table consisting of `mean`
(simple average), `stddev` (standard deviation aka mean of the
variance), `min` and `max`, all in milliseconds, as well as `n` as the
number of samples taken.
