Remove broken datetime input transformer

Epgsql expects a timestamp to come an erlang_time() tuple.  This
transform was converting that to an invalid tagged-tuple of form
{datetime, erlang_time()}.

There was a bug in the transform (using _M for both month and minute) that
 meant it only pattern matched on certain cases (when month == minute) meaning
it appeared as an intermittent error, causing a badmatch in pgsql
pgsql_idatetime:date2j/1.

This commit juts removes the bad transform completely since it's the
wrong thing to do.

change one of the examples so that month==minute in the test to catch regressions of CA-531
Merge branch 'jc/CA-531/timestamp-transformers'
sqerl_gobot parse_transform

The `sqerl_gobot` got it's name because at first, it seemed like a
transformer knockoff. Also, there's another module called
`sqerl_transformers` and I thought calling it `sqerl_transform` would
get too confusing.

down version of `exprecs`. Since exprecs was built to allow you to
export multiple records from a single module, it had to a lot more work
than we needed. The exprecs-ish functions we've preserved are:

* `'#new'/0`
* `getval/2`
* `'fromlist/1`
* `fields/0`
* `'#is'/1`
* `setvals/2`

This PR suggests that functions with the intent of being called mostly
by `sqerl_rec` internals be prefixed with a `#`, but people can use
whatever functions they want.

We've also exported a type to encapsulate the record completely, take
the following record:

```erlang
-record(notifier_config_object, {
    name :: string(),
    rank :: string(),
    serial_no :: integer(),
    non_typed
}).
```

It exports the following dialyzer types:

```erlang
-type notifier_config_object() :: #notifier_config_object{}.

-type attr() :: name | rank | serial_no | non_typed.

-type prop() :: {name, undefined | string()}
              | {rank, undefined | string()}
              | {serial_no, undefined | integer()}
              | {non_typed, any()}.

-export_type([{attr,0},{notifier_config_object,0},{prop,0}]).
```

have been tabled from this PR. The code still exists in some branch and
we can revisit this in the future.