Add ability to align arrays contents.

[icemac]

I have long lines of text in an array and want to keep it human readable by putting each entry on an new line. Currently I have the following possibilities:

>>> import toml
>>> foo = dict(bar=['a long long line of test', 'another long long line of text'])
>>> print(toml.dumps(foo))
bar = [ "a long long line of test", "another long long line of text",]

>>> print(toml.dumps(foo, toml.TomlArraySeparatorEncoder()))
bar = [ "a long long line of test", "another long long line of text",]

>>> print(toml.dumps(foo, toml.TomlArraySeparatorEncoder(separator=",\n   ")))
bar = [ "a long long line of test",
    "another long long line of text",
    ]

The last variant looks best but still does not have all entries alined. My PR adds this ability:

>>> print(toml.dumps(foo, toml.TomlArraySeparatorEncoder(separator=",\n   ", indent_first_line=True)))
bar = [
    "a long long line of test",
    "another long long line of text",
    ]

Additionally the last entry in the array gets an extra space to the opening and closing brackets are equally surrounded by spaces in the default version (This was necessary to fit my use case as otherwise the closing bracket would be indented a space character too little.):

>>> print(toml.dumps(foo, toml.TomlArraySeparatorEncoder()))
bar = [ "a long long line of test", "another long long line of text", ]

Is there a chance to get this PR landed in the project?
Are the suggestions to improve it?

[codecov-io]

Codecov Report

Merging #343 (ba55d7f) into master (3f637db) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #343      +/-   ##
==========================================
+ Coverage   89.74%   89.77%   +0.02%     
==========================================
  Files           5        5              
  Lines        1063     1066       +3     
==========================================
+ Hits          954      957       +3     
  Misses        109      109              

Impacted Files	Coverage Δ
toml/encoder.py	88.50% <100.00%> (+0.17%)	⬆️

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[icemac]

Is there anything I can do to get this PR merged?

[icemac]

Lost hope that this will get merged, so closing it.