databases/cego: 2.30.15 -> 2.30.17

• Fixed for point-in-time recovery, Date format handling was not done correectly
• Elimination of BUFFERPOOLHASHKEY. The bufferpool position is now calculated based on the page offset of the corresponding datafile ( this information is provided by CegoFileHandler::getRegPageOffset ) This leads to a much better distribution and usage of the available buffer pool pages
• Fix in CegoTableManager::createBTree, the creation of the btree object must be done in a dedicated exception block, otherwise the btree object is dropped, if it already exists.

Submitted by: Bjoern Lemke <lemke@lemke-it.com>