gzip and gunzip should have -k (--keep) option like bzip2 and bunzip2

[Shriramana Sharma]

Hello and thanks for gzip.

bzip2 and bunzip2 have an option -k or --keep which prevents deletion of 
the input file(s) during compression or decompression which is the 
default behaviour.

It is very difficult to use gzip and gunzip without these options. 
Please add them to the next version of gzip.

Thanks.

Shriramana Sharma.