refactored params dictionary implementation
refactored params dictionary implementation

 * do handle colliding URL parameter names (e.g. colliding with functions defined on the dictionary object) by prefixing their key with "&"
 * only add URL parameter value as multiple, if the same value was not already specified, e.g. for "?key1=1&key1=1", "key1" will not be treated as multiple
 * changed internal (i.e. private) handling for is-mulitiple marker and keys fieldname by adding prefix "_" to the field names

mmig/mmir-lib