All make-based projects: Use $(MAKE) instead of 'make' for all commands, per the standard requirements for nested Makefiles.  See GNU Make docs for $(MAKE) for details.
openssl.cmake: Forbid openssl to build in parallel.  The openssl makefiles are not set up properly for parallel builds.
Readme: Added notes about building Qt on X11
python.cmake: Added an optional cmake cache variable to enable building a debug version of Python.
ilastik.cmake: Update lazyflow submodules when pulling from git.
vigra.cmake: Updated git tag.