Use htmlspecialchars to fix XSS in some example scripts

Fix #63 - Fix open_basedir restriction in effect with lame binary path - must set Securimage::$lame_binary_path = ""; to avoid

Fix #94 - Fix for illegal string offset error if getCode() is invoked with no previous session or database value

Possibility to make the captcha's input required

Add possibility to change the JavaScript url.

Fixing PHP 7.4 Incompatibility : Curly brace syntax #97

I added to the captcha's input text a required tag in order to oblige the user to fill it.

It could be disable with  'input_required' => false. 

For example:
Securimage::getCaptchaHtml(array('input_required' => false))

Increase CAPTCHA difficulty; rewrite drawWord(); add 4 new difficulty settings (use_random_spaces, use_random_baseline, use_text_angles, use_random_boxes)

.htaccess files Apache 2.4 compatibility update

The .htaccess files used to restrict access to specific directories
follow the Apache 2.2 mod_authz_host module syntax [1] (Order, Allow,
Deny).

Apache 2.4 introduced a new module mod_authz_core [2], with a different,
incompatible directive (Require). Consequently, unless the compatibility
module access_compat is enabled, the obsolete ones will cause Apache
configuration errors to occur when the .htaccess file is read.

To avoid this, the .htaccess files are modified to use the new syntax
when an Apache 2.4 server is detected, and fall back to the old
directives otherwise.

[1] https://httpd.apache.org/docs/2.2/mod/mod_authz_host.html
[2] https://httpd.apache.org/docs/2.4/mod/mod_authz_core.html

Fixed regex in replaceElements

Update example_form.ajax.php

I have fixed 2 syntax error

line 23 and line 93.
Just a colon and a semilon

The old regex replace the first parameter that end with ‘id’. The new
one use & or ? to catch exactly the ‘id’ param.

Exclude some dirs and files from repository auto-generated ZIP archives