XMLRPC rework

small rework of xmlrpc code

- RemoteApi - PHP interface of exported methods
- XmlRpcServer - Bridge of RemoteApi and XMLRPC

all public methods of RemoteApi class are eported, param and return values are controlled from phpdoc annotations
 
also disabled base64 encoding, it seems to work with current PEAR XMLRPC package
also xmlrpc spec has base64 type, which can be enforced if there's still problem

this changeset allows easily replacing xmlrpc implementation, altho there aren't many around