added external api for Elliptic Curves Extension.
added api tests for Elliptic Curves Extensions.
added Elliptic Curves Extensions implementation and configuration.
added curve names extension to all extensions
removing unused curve names.
removing missing extensions
exporting pkCurve info to ctx and ssl
validating curves
writing curves in the right order. (reverse)
improved curve validation.
fixed return codes
added protection for missing HAVE_TLS_EXTENSIONS