Support lists of values

[kynikos]

By default, if a key is duplicated in a section, its value is assigned with the cascading rule.
Optionally, instead, interpret this as the definition of a list, with each duplicated key hosting an item:

option = aaa
option = bbb
option = ccc

Alternatively, support interpreting numbered suffixes as list items, for example:

option[1] = aaa
option[2] = bbb
option[3] = ccc

Or distinguish lists from normal keys with a special prefix:

*option = aaa
*option = bbb
*option = ccc