Solve #316 - Add option to replace in used in always_for_in

[domluna]

Add an option for_in_replacement, that works alongside always_for_in whereby you can specify an alternative to in.

Can be used when always_for_in is true to replace in with ∈ (\in), or = instead:

for a = 1:10
end
# formatted with always_for_in = true, for_in_replacement = "∈"
for a ∈ 1:10
end

[iblislin]

Suggested change

	function valid_for_in_op(s::String)
	valid_for_in_op(s::String) = s ∈ ("in", "=", "∈")

And... maybe we can run this function in constructor of Options?

[domluna]

that makes a lot of sense

[exaexa]

Hi all, I'd really love to have this merged&released, is there anything I could potentially help with to get this through?

[domluna]

Hi all, I'd really love to have this merged&released, is there anything I could potentially help with to get this through?

Probably just has to be rebased. And also do this #380 (comment)

[exaexa]

OK, I'll push it to my fork ASAP. The rebase will be slightly challenging it seems.