Make email obfuscation optional

[AMDmi3]

I've noticed that my email is obfuscated in Doxygen output, and that's definitely not that I want. There was no option to disable this behavior and I've added one. The default behavior is unchanged, but specifying OBFUSCATE_EMAILS = False in Doxyfile disables obfuscation.

Here's an example case:

README.md: Dmitry Marakasov <amdmi3@amdmi3.ru>
Doxyfile1: USE_MDFILE_AS_MAINPAGE = README.md
Doxyfile2: USE_MDFILE_AS_MAINPAGE = README.md
Doxyfile2: OBFUSCATE_EMAILS = False

Diff for generated html/index.html with Doxyfile1 and Doxyfile2:

--- html/index.html	2021-12-29 17:03:55.598158000 +0300
+++ html/index.html	2021-12-29 17:03:59.660321000 +0300
@@ -65,7 +65,7 @@
   <div class="headertitle"><div class="title">My Project </div></div>
 </div><!--header-->
 <div class="contents">
-<div class="textblock"><p ><a class="anchor" id="md_README"></a> Dmitry Marakasov <a href="#" onclick="location.href='mai'+'lto:'+'amd'+'mi'+'3@a'+'md'+'mi3'+'.r'+'u'amdmi<span style="display: none;">.nosp@m.</span>3@am<span style="display: none;">.nosp@m.</span>dmi3.<span style="display: none;">.nosp@m.</span>ru</a> </p>
+<div class="textblock"><p ><a class="anchor" id="md_README"></a> Dmitry Marakasov <a href="mailto:amdmi3@amdmi3.ru">amdmi3@amdmi3.ru</a> </p>
 </div></div><!-- PageDoc -->
 </div><!-- contents -->
 <!-- start footer part -->

[doxygen]

@AMDmi3 Can you motivate why you do not want obfuscation? The idea behind it is to avoid that web scrapers can easily collect the mail addresses and start sending spam.

[albert-github]

Normally when you would click on the link the default mailer would open with the right address.
What is the reason that you want to have your email address readable in the documentation?
Wouldn't it be a easier potential way to get spam mail?

[AMDmi3]

@doxygen @albert-github it should be obvious, I want my email to be readable both as text (without .nosp@m. garbage) and also be a valid link, including for people with disabled javascript. The spam problem is fictional for me.

[doxygen]

Please follow doxygen's coding style, i.e. matching braces should be aligned on the same column. I had already fixed this, but your force commit undid my changes, so please do them yourself this time.

[AMDmi3]

Done

[AMDmi3]

Oh, and I've just realized one thing: the link text is in fact intended to be readable. For me it is not though, and that's caused by content-security-policy: HTTP header which disables embedded styles. visibility: hidden bit should also be moved into the CSS and class should be used in <span> insertions. Submitted as #8992.

[albert-github]

Shouldn't this option also have the depends='GENERATE_HTML' as it is just for HTML?

[doxygen]

Good point, I fixed it: 5da7df8