This replaces uses of:

	memcpy(dst, src, strlen(src))

with:

	strcpy(dst, src)

This fixes issues with reading past the end of the copied buffer
(e.g. when processing word-based replacements for emoji characters)
by ensuring that the destination buffer is null terminated.

Reported by Michael Curran <[email protected]>

Outside of Linux platforms, sha1 hashing from the command-line is accomplished
by commands other than sha1sum. OSX uses shasum and FreeBSD uses sha1, so I've
added in detection for the appropriate command before falling back and failing
the test.

This is to support additional logic (i.e. testing the ReadClause
function) in the test functions.

These tests are limited in scope and should really be part of a
more comprehensive API tests.