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.

2015/guidelines.txt

@@ -677,7 +677,7 @@ JUDGING PROCESS:
         twitter handle(s) (if provided and if anonymity was not requested)
         country code(s) of the author(s)
 
-    After the initial announcement, we attempt to send EMail to the
+    After the initial announcement, we attempt to send an email to the
     authors of the winning entries.  One reason we do this is to give
     the authors a chance to comment on the way we have presented their
     entry.  They are given the chance to correct mistakes and typos.  We
@@ -829,12 +829,12 @@ ANNOUNCEMENT OF WINNERS:
 
 FOR MORE INFORMATION:
 
-    You may contact the judges by sending EMail to the following address:
+    You may contact the judges by sending an email to the following address:
 
 |       q.2015@ioccc.org        (do not submit entries to this address)
 
 |   You must include the words 'ioccc 2015 question' in the subject of your
-    EMail message when sending EMail to the judges.
+    email when sending email to the judges.
 
     Questions and comments about the contest are welcome.  Comments about
     confusing rules and guidelines are also welcome.

2015/rules.txt

@@ -234,7 +234,7 @@ FOR MORE INFORMATION:
 
 |       ioccc 2015 question
 
-    in the subject of your EMail message when sending EMail to the judges.
+    in the subject of your email when sending email to the judges.
 
     The rules and the guidelines may (and often do) change from year to
     year.  You should be sure you have the current rules and guidelines