Unpack refactor and improved isAssoc documentation

Unpack

• Replaced internal method argument with mode argument
• Added 4 modes of handling array at highest nesting depth
  • UNPACK_ALL (default) - unpack every nested array

    $arr['foo.bar.0'] = 'a';
    $arr['foo.bar.1'] = 'b';

  • UNPACK_PRESERVE_LIST_ARRAY - preserve list type array

    $arr['foo.bar'] = ['a', 'b'];

  • UNPACK_PRESERVE_ASSOC_ARRAY - preserve associative array

    $arr['foo.bar'] = ['a' => 1, 'b' => 2];

  • UNPACK_PRESERVE_ARRAY - work as both of options above combined
• For examples check out unpack test method testUnpack
• Examples in documentation coming soon

isAssoc

• Clarified in PHPDoc how both values of $strict flag works