Amber 20 is updated

Amber version 20 has been updated and installed with Intel and GNU compilers and MVAPICH2 on Owens and Pitzer.  These include Amber and AmberTools.  Usage is via the module amber/20.  For installation details, such as, available packages and example batch scripts, use command:  "module help amber/20".  For help loading an installation, use command:  "module spider amber/20".