Bash: fix bug in findfiles() declaration

I had used "function findfiles()". The "function" keyword doesn't exist
in Bash, so I removed it.
Bash: create a set of helper functions for scripts

The non-executable file ~/bin/helpers.sh contains a collection of
functions which are useful for other functions in Bash scripts. A script
should source this file and then call the desired functions.

This file is not meant to be run directly by the user (and hence is not
executable.) However, if you really want to call these functions
directly, simply source the file in your Bash session and call them.

To start, there are three functions:

* get_script_name(): echoes the name of the script file the user called
(useful for printing help messages, etc.)

* get_script_path(): echoes the full path and filename of the called
script (useful if you want to write out a full command for another
script to later call you.)

* check_url(): uses cURL to check if we can retrieve the URL without
errors (used in hman, for example, to check if a man page exists on
Apple.com, instead of creating it ourselves.)
Bash: `hman` will try to open Apple.com's version

The `hman` command will check to see if the manpage is a standard
system manpage. If so, it will check Apple.com's website to see if the
manpage exists there. If it does, it opens that version in the browser.
If it does not exist, or the manpage is a non-standard one (for
example, from homebrew,) it continues to generate a local HTML version
of the manpage itself, as usual.