Fix ToMap for tables in nested mixed-type arrays

[mstetson]

I wasn't thorough enough in my earlier PR. #453 fixed tables in mixed arrays, but only in the top-level array, not in any nested array. This updated fix scans arrays recursively looking for tables. It supports constructs like this:

UglyValue = ["blah", [
    {foo = "bar"},
    {baz = "quux"},
]]

[codecov]

Codecov Report

Merging #455 (6642afc) into master (1bd9461) will decrease coverage by 0.08%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master     #455      +/-   ##
==========================================
- Coverage   93.60%   93.51%   -0.09%     
==========================================
  Files          10       10              
  Lines        2268     2268              
==========================================
- Hits         2123     2121       -2     
- Misses        105      106       +1     
- Partials       40       41       +1     

Impacted Files	Coverage Δ
tomltree_write.go	94.15% <81.81%> (-0.65%)	⬇️

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[pelletier]

Thanks! Is there a case where this branch is taken?

	if tv, ok := v.(*tomlValue); ok {
		v = tv.value
	}

If yes it's probably worth a test, if not we can get rid of the code :)

[pelletier]

Merged with #461

Thank you!

[mstetson]

Thanks! Sorry I left you hanging there.