add MappedBufferIntern

- add MappedBufferINtern which is a DeviceBuffer based on cuda mapped memory
- cleanup all interfaces which hard use DeviceBufferIntern to use the interface of DeviceBuffer
- extend interface of Devicebuffer
Fix GridBuffer Destructor

In case the GridBuffer is not running for the whole simulation,
we have to make sure that the transaction dependencies between the
allocated memory (host, device, mapped) and the GridBuffer
will be sheduled right.
Merge pull request #1 from ax3l/topic-bufferRedesign

Fix GridBuffer Destructor
change annotated points
delete old comment
Merge pull request #169 from psychocoderHPC/topic-bufferRedesign

add MappedBuffer