Integrate space-efficient SA algorithm.
Fixed compile error
Buffer should not be zero sized.

Fixed division by zero problem in line 58:

m_begin = (idx/m_buffersize)*m_buffersize.

Interestingly g++4.8.2 appears to handle
this expression for m_buffersize==0, while
g++4.7 does not.
Merge pull request #172 from simongog/space_efficient_saca_integration

Integrate space-efficient SA algorithm.