Change ArgSpec::setValue to ::addValue

[remkop]

...and move the logic that initializes arrays, collections and Maps from the Interpreter class to the model.

Related to #182 (support annotating methods with @Option and @Parameters):

@Option(name = "-x", description = "Getter method returns mutable list")
List<Integer> getIntegers() { ... }

@Option(name = "-y", description = "Setter method replaces full collection")
void setLongs(List<Long> values) { ... }

@Option(name = "-z", description = "Mutator method adds single value")
void addDouble(double dbl) { ... }

For maps, adding individual key-value pairs as they are found on the command line is more complex:

@Option(name = "-a", description = "Getter method returns mutable map")
Map<Integer, String> getIntegers() { ... }

@Option(name = "-b", description = "Setter method replaces full collection")
void setLongs(Map<Long, String> values) { ... }

@Option(name = "-c", description = "Mutator method adds single value")
void addShort(short shrt, String value) { ... }

[remkop]

Based on experience with rewriting groovy.util.CliBuilder based on picocli (#258), there is no need for this API change. #182 can be implemented with IGetter and ISetter implementations that bind the option or positional parameter to a method invocation. Details are on the #182 ticket.