Change references of 'EMail' to '[Ee]mail'

Depending on if it was the beginning of the sentence the EMail would
become 'Email' or 'email'.

Some references of 'Email' were changed to 'email' as well as those were
not in the beginning of a sentence.

A few places some consistency of capitalised email address (made lower
case) were changed to match other places of the same pattern.

CONTRIBUTING.md

@@ -5,13 +5,13 @@
 0. Verify that the <A HREF="https://www.ioccc.org/index.html#enter">IOCCC is open</A> for submissions.
 1. If the IOCCC is open, you need to register as a contestant.
 See: <A HREF="https://www.ioccc.org/index.html#enter">how to enter</A> for how to register.
-2. Once you have been registered, you will receive and Email message for how to
+2. Once you have been registered, you will receive and email message for how to
 prepare your entries for submission,
 and how to upload the compressed tarballs to our submission portal.
 3. Once the <A HREF="https://www.ioccc.org/index.html#enter">IOCCC</A> closes,
 the judges will select the <A HREF="https://www.ioccc.org/years.html">winning entries</A>,
 announce them on the <A HREF="https://fosstodon.org/@ioccc">@IOCCC mastodon feed</A>,
-notify the winners via Email using their previously registered Email address,
+notify the winners via email using their previously registered email address,
 and upload the winning code to the <A HREF="https://github.com/ioccc-src/winner">ioccc-src/winner</A> repo
 which in turn will cause them to be displayed on the  <A HREF="https://www.ioccc.org/years.html">IOCCC winners page</A>.