Piwik modifications to libs/

In general, bug fixes and improvements are reported upstream. Until these are included upstream, we maintain a list of bug fixes and local mods made to third-party libraries:

• HTML/Quickform2/
  • in r2626, php 5.1.6 incompatibility
  • in r3040, exception classes don't follow PEAR naming convention
• sparkline/
  • in r1296, remove require_once
  • empty sparklines with floats, off-by-one errors, and locale conflict
  • in 270821ed (https://github.com/piwik/piwik/pull/8410) PHP7 compatibility: renamed the constructors
• tcpdf/
  • in 6f945465 fixed a bug reported in the forums
  • in 566c63a5 fixed another couple bugs with fopen throwing warnings
• Zend/
  • strip require_once (to support autoloading)
  • in r3694, fix ZF-10888 and ZF-10835
  • ZF-10871 - undefined variables when socket support disabled
  • fix #6980 ("Array to string conversion") in Zend/Session/Exception.php
  • fix Zend/Validate using deprecated iconv_set_encoding()
  • Make sure sessions work when storing notifications
• materialize/
  • in materialize.min.css removed the loading of Roboto fonts as the paths do not match and couldn't be loaded. Also we do not want to load as many different font styles of Roboto font.