Fixed CORE-4630: Segfault in server caused by bad packet

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_1_Release@60322 65644016-39b1-43b1-bf79-96bc8fe82c15
Updated docs & version info.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_1_Release@60324 65644016-39b1-43b1-bf79-96bc8fe82c15