Version 1.8 (#280)

* Version bump

* Update README

* Apply suggestions from code review

Co-Authored-By: Philip Top <top1@llnl.gov>

* Adding mark for deprecated items

Author: henryiii

LICENSE

@@ -1,11 +1,11 @@
-CLI11 1.7 Copyright (c) 2017-2019 University of Cincinnati, developed by Henry
+CLI11 1.8 Copyright (c) 2017-2019 University of Cincinnati, developed by Henry
 Schreiner under NSF AWARD 1414736. All rights reserved.
 
 Redistribution and use in source and binary forms of CLI11, with or without
 modification, are permitted provided that the following conditions are met:
 
 1. Redistributions of source code must retain the above copyright notice, this
-   list of conditions and the following disclaimer. 
+   list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.