Removed lmfit from third parties
Added installation of Plugin headers.
PluginLib heades are now installed in pluginslib/c and pluginslib/cpp
Added a BUILD_TEST_TOOLS target, keeping the BUILD_TESTS target.
Build only cxx test app and rrc if BUILD_TEST_TOOLS are selected
Don't install the test scripts..
Removed .lib files from plugin install
Added files that will over write files from the libSBML install
Added Copying.txt file
Merge pull request #60 from TotteKarlsson/more_on_distro

Removed lmfit from third parties