0024870: Provide OCCT RTTI test cases

0024870: Provide OCCT RTTI test cases

Test commands for checking performance and functionality of OCCT handles and RTTI added.
New test case added for that: test perf fclasses handle.

Implementation of opencascade::handle improved to enable compile-time error if two handles of incompatible types are compared.
Comparison of handle to NULL is not possible any more; method IsNull() should be used instead.

Method LDOM_MemManager::Doc() is removed to avoid cyclic dependency of headers; constructor of LDOM_Document(LDOM_MemManager&) is used directly instead.

Inclusion of headers corrected for compilation after previous patch.