omegalib: v7.0

This is the first release to be distributed as binary installer for both OSX and Windows. Support for display systems has been greatly improved: display systems are now loaded at runtime based on their name in the configuration file. New display systems can be added to omegalib just by adding their dll or shared library to the binary distribution. The Omegalib core ships with two display systems: Equalizer and GLFW. Other major changes since v6.0 include python multithreading support, improved logging and several bugfixes to resource allocation and cluster shutdown