2.0

• forked from E57RefImpl
• removed all but the main sources for reading and writing E57 files
• now requires C++11
• now requires cmake 3.1+
• no longer uses BOOST
• multiple fixes for compilation on macOS
• fix a couple of fallthrough bugs which would result in undefined behaviour
• turn off E57_MAX_DEBUG by default
• improve file read times
• add a checksum policy (see ReadChecksumPolicy in E57Format.h) so the library user can decide how frequently to check them
• remove "big endian" byte swap code (not sure it was working and no way to test)
• lots and lots of code cleanups
  • refactored the code into multiple files
  • removed unused macros and code
  • remove non-useful comments
  • add proper initialization of class and struct members
  • modernize using c++11
• [Windows] add cmake option ()USING_STATIC_XERCES) to tell the build if you are using a static Xerces lib