add main cxl.rb, Cxl::VERSION, and initial CLI processing

bin/cxlc

@@ -5,6 +5,6 @@ $LOAD_PATH << "#{lib_dir}/cxl/lib"
 $LOAD_PATH << "#{lib_dir}/yawpa/lib"
 $LOAD_PATH << "#{lib_dir}/whittle/lib"
 
-require "cxl/cli"
+require "cxl"
 
 exit(Cxl::Cli.run(ARGV.dup))