r4229 bugfix: IPv6 was broken with PHP older than 5.2

r4229 bugfix: IPv6 was broken with PHP older than 5.2
all(hopefully) implicit conversions from IPv6Address class into string using magic __toString class method was replaced by exclicit toBin() method calls.

affected functions:
 renderSeparator
 getPageNumOfIPv6
 scanIPv6Space
 bindIPv6ToObject
 getIPv6AddressNetworkId
 updateV6Address
 updateIPv6Bond
 unbindIPv6FromObject
 createIPv6Prefix
 IPv6NetworkCmp

IPv6Address class:
 new field-proxy function toBin()
 magic method __toString was substituted by temporary backtrace-showing code to find hidden calls to magic method before the release occurs.