Add whitelisting functionality
Add whitelisting functionality

We can now specify our own whitelisting file, overriding the default of
'lenchk-excludes' which must stay in the same directory as lenchk, at
least for now. The custom file can be wherever you want it, however.

I'd like to use the `readarray`/`mapfile` BASH built-in for populating
the array variable, but it didn't seem to want to work, so I just went
for another `while read` loop. It's working very nicely as-is, though.

I've changed the required whitelist format to one of simplicity: one
filename per line. Why the previous format? Because of files which may
have a newline character in them, but I realised in this environment
that's just not going to happen; force of habit, I guess.

I'd like to allow users to be able to whitelist entire directories, but
I don't see that being so high on the priority list, for now.

What do you think?

chubin/cheat.sheets,chubin/cheat.sheets