genometools.h wrapped in #ifdef __cplusplus

allows to include genometools.h into C++ projects
Merge pull request #33 from gordon/master

genometools.h wrapped in #ifdef __cplusplus
fix problem with impossible events in self-trained BSSM

patch by Volker Brendel
Merge pull request #34 from gordon/master

fix problem with impossible events in self-trained BSSM