changed oF/addons to a C project for eclipse

addons is still no C project for eclipse. this way it isn't possible to rebuild the index or to use code completion, call hierarchy or symbol following in its full capacity. 
(for example try to jump from ofxSlider.h to ofxBaseGui via F3 in line 7)

I always import from "existing code as makefile project" instead of "existing projects ..." when it comes to oF/addons. I'm using the Linux GCC Toolchain for the indexer.

for me it works fine but I have to rebuild the indexer from time to time.