Make smallest area concept optional

[SwissalpS]

• Reverts default behaviour to before Use smallest area at given position #79
• Allows experimental enthusiasts to use Use smallest area at given position #79 by togglig a setting
  see comments in Use smallest area at given position #79

The diff may make it look like much changed, but I only wrapped current and previous behaviour into an if then else clause and added the setting in settingtypes.txt.

[SmallJoker]

This code is duplicated. Please offload it to a function or find out a smarter way.

Hint:

local arealist
if areas.config.use_smallest_area_precedence then
	arealist[???] = self:getSmallestAreaAtPos(pos)
else
	arealist = self:getAreasAtPos(pos)
end

for _, area in pairs(arealist) do

end

[SwissalpS]

This part of code is used a lot, so I took the time to write two variants and benchmark them. The results did not show any clear difference in execution speed on my old laptop in a devtest game with only areas and playerfactions mods.
To keep it simple the test world had no factions or areas defined at all.
Variant A (function):
https://github.com/SwissalpS/minetest_areas/blob/665d308c99bf771d77ef738c17c97d347039800e/api.lua#L118-L171

branch function

Variant B (table):
https://github.com/SwissalpS/minetest_areas/blob/71ae3c0a6ca80698f364142d80342bceb7a48214/api.lua#L118-L159

branch table

Variant B uses 12 lines less, I prefer Variant A by a slim margin for its readability, what do you think?

[SmallJoker]

Whether to pick A (helper func) or B (new table) is entirely subjective. Though, I find it interesting that the local function showed no performance impact. LuaJIT might realize that none of the caller's function stack is needed, thus resulting in a negligible performance difference.

I prefer variant B (L126-128 could be removed too) for having more linear code flow (top to bottom) and smaller branches (as in LoC).

Your preference - variant A - is also OK. It could further be reduced in line count by moving the remaining access checks into the helper function (name would be subject to change).

Implement what you think is easier to understand. I'll be fine with either.

[SwissalpS]

I find it interesting that the local function showed no performance impact.

Maybe my computer has way to much on its hands to be a good platform for benchmarks. Other processes might influence the results.

LuaJIT might realize that none of the caller's function stack is needed

I don't think my setup is using LuaJIT. On another repo I was using table.pack which the CI of github didn't have and somebody comented that LuaJIT doesn't have that.

L126-128 could be removed

OK, I did feel it made clearer what was going on, but it works since my other concern has disappeared with these changes.
Instead I added ", _" in line 124 to make clear why the variable smallest_area is needed:

local smallest_area, _ = self:getSmallestAreaAtPos(pos)

[SmallJoker]

Works. Tested with setting = false and = true, local server.

Will merge in a few days unless there are objections.