Clipp Versions Save

• fixes issue

• fixed issue
• README: added quick reference and fixed some typos

• fixed handling of empty args
• added "with_suffix" and "with_suffix_short_long"
• fixed typos in README and code comments

Added usage line and documentation text formatting capabilities. Documentation text will now be wrapped according to the new formatting setting .last_column(int) which defaults to 100. Note that if you want the text to be wrapped according to the current terminal window width you need to use some other library to query terminal/window properties.

introduced "greedy" parameters

tests pass with g++5, 6, 7 clang++3.8, 3.9, 4.0, 5.0 MSVC 14.11.25547 tests run cleanly through valgrind memcheck with g++ 5