Add shortcuts for selection and version options in xclip

[erikd234]

This commit introduces two new command-line shortcuts for the xclip utility. The '-s' shortcut has been added for the '--selection' option, allowing users to specify the X selection (primary, clipboard, secondary, or buffer-cut) more conveniently. Additionally, the '-v' shortcut for '--version' has been implemented, making it easier to check the version of xclip. The help message in xcprint.c has been updated accordingly to reflect these new shortcuts.

Also I added in the help command the short forms of the differetn selection targets (p, s, c , and b)

If you want me to update the to also use -s I can, manual testing works and the tests pass after changes.