Process.parse_arguments escapes quotes when it should not

[erdnaxeli]

Hi,

I once wrote a lib to do exactly the same thing as the new Process.parse_arguments, so I tried to run my tests with the new stdlib method. And this one does not work:

require "process"

pp ARGV
pp Process.parse_arguments(%(this 'is a "'very wei"rd co"m"mand please" don't do t'h'a't p"leas"e))

$ crystal y.cr -- this 'is a "'very wei"rd co"m"mand please" don't do t'h'a't p"leas"e
["--", "this", "is a \"very", "weird command please", "dont do that", "please"]
["this",
 "is a \"very",
 "wei\"rd",
 "co\"m\"mand",
 "please\"",
 "don't",
 "do",
 "t'h'a't",
 "p\"leas\"e"]

The thing is 'something "quote' keeps the quote, because it is enclosed in single quotes, but something"else"quote is just a string concatenated to another string concatenated to another one. The stdlib method keeps all quotes whether they are quoted or not, which is incorrect.

The split of the string is also incorrect. Specifically something"else with spaces"quote are 3 strings concatenated, and it should not be splitted on spaces as their are quoted. It seems also that some quotes are ignored (like in don't)?

I will try to propose a PR.