change CCP4reader.hpp to CCP4Reader.hpp for case-sensitive systems
fix typo ccp4in -> ccp4gz
Merge pull request #3 from wojdyr/gzseek-typo

fix typo ccp4in -> ccp4gz
Merge pull request #2 from wojdyr/case-sensitive

change CCP4reader.hpp to CCP4Reader.hpp for case-sensitive systems
added #include <cstddef> for NULL