Two different fixes: Oracle and Serialization

I managed to muck up the pull-request and have included two disparate fixes. One fixes a problem with Oracle Calls related to CharSetToUnicode (and vice versa) by correcting the marshalling from U4 to SysUInt (these APIs require size_t type values for the string sizes which are 64-bit values).

The second fix is part of the 11294 fix. The variable names that Mono's implementation of Collection.cs differs from .NET's which means that when serializing/deserializing on one platform and doing the reverse on the other, we fail. So part of this fix is to make the variable names the same. The second part of this fix is to remove the serializable attribute from a couple of variables as they aren't needed by the serialization/deserialization process (this will make the variable list match that of .NET).

I managed to screw up the pull-request of the bulk of the 11294 fix by pushing to master and not my forked repo. The fixes can be found under f19a364025edc23559597e24ea332890f3b1e0ff