Igcs 75 coreplot update

- Removed old core-plot headers and compiled static lib.
- forked core-plot to FW repository and added it as a submodule
- Made core plot a build dependency of our targets
- Added proper core-plot header search path to top level iGCS project file
- point submodule to latest stable release (1.4)
- might be some more build issue to work out... going to do a from scratch build this afternoon.