get_sha1() was deprecated in a5314a2ff4cb503ff41da13ffd0e907f49ee4009,
so formally $sha1 was also formally deprecated but not commented.
Clarify we really want to deprecate $sha1 too.

Updates CHANGELOG.md.

This typo has been around for a while. Well, not anymore.

Claiming copyright for parts of UploadedFile.class.php and
settings.inc.php as per previous change, which introduced PHPDoc
comments.

The other files where edits were made in previous commits are
non-substantial and thus most likely not under copyright.

Add file summaries, @copyright tags and other comments. Covers majority
of the PHP code base now. I have avoided being too verbose and omitted
some potential tags.

Most visibly to the user, this comments every user configurable setting
and clarifies what some of the options do.

POMF_DB_USER and POMF_DB_PASS are not rendered perfectly in
phpDocumentor version 2.8.5. This is a sacrifice I made in attempt for
not being too verbose and obvious.

Response class gets a @todo for being a god object.

There are two issues with get_sha1():

- The function name doesn't follow the PSR-2 coding style guide for
  function naming, followed in Pomf since version 2.0.0.
- SHA-1 is no longer considered resilient to collisions, versus SHA-256.

In current plans, this feature is to be replaced with getHash() or
similar function name in the next major version (Pomf 3.0.0).

For consideration for future SHA-256 hashing implementation, the MySQL
schema's hash value needs to be changed from char(40) to char(64) to
accommodate the longer SHA-256 length of 64 bytes in hexadecimal string.

get_crc32() was removed in commit ea6a7a0194 and never in use in the
code. It seems Eric forgot to remove this property.

Interestingly, static/classes/UploadedFile.class.php is not licensed
under Expat license. Because it was posted in PHP.net comments, I
believe it's under the PHP license.