Comment drawtext and drawfont

* src/R/imageTrans.R: EBImage has depricated drawtext and drawfont with not
obvious replacement. We wont put the annotations in the images for now.
Make a new release for R 3.0.1
Add method to estimage 50% dates.

	* CMakeLists.txt: Include new method in the build.
	* docs/man/eip.get_50_dates.Rd: New method documentation.
	* src/R/ecoip.R: New method to estimate 50% onset dates.
Add install method to README