sandwich tests added
slightly improve build infrastructure
sandwich: fixed implicit ref to temp copy

Exposed by test "simple" with -O2
sandwich: fixed SeekToLast

By some reason this bug had exposure in Sandwich/Txn/Memory, but had no
visible effect in Sandwich/Memory variant.
use host order

Since leveldb is platform dependant anyway lets use host order.
Also added a big sandwich test to check order specific code.
resolve symbol duplication

During integration met problem with symbol duplication caused by missing
inline/constexpr. Also added a dummy executable that links together all
tests to monitor such cases.
compatible with gcc 4.7.3

Sorry guys, target project bound to that version.