Refactor string handling functions

bibtexbrowser.php

@@ -74,7 +74,7 @@ if (defined('ENCODING')) {
 
 // shall we load MathJax to render math in $…$ in HTML?
 @define('BIBTEXBROWSER_RENDER_MATH', true);
-@define('MATHJAX_URI', '//cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_HTML.js');
+@define('MATHJAX_URI', '//cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/config/TeX-AMS_HTML.js?V=2.7.1');
 
 // the default jquery URI
 @define('JQUERY_URI', '//code.jquery.com/jquery-1.5.1.min.js');
@@ -959,10 +959,8 @@ function xtrim($line) {
   // 2010-06-30
   // bug found by Thomas
   // windows new line is **\r\n"** and not the other way around!!
-  $line = str_replace("\r\n",' ', $line);//windows like
-  $line = str_replace("\n",' ', $line);//unix-like
-  // we also replace tabs
-  $line = str_replace("\t",' ', $line);
+  // according to php.net: Proncess \r\n's first so they aren't converted twice
+  $line = str_replace(array("\r\n", "\r", "\n", "\t"), ' ', $line);
   // remove superfluous spaces e.g. John+++Bar
   $line = preg_replace('/ {2,}/',' ', $line);
   return $line;
@@ -988,11 +986,9 @@ function latex2html($line, $do_clean_extra_bracket=true) {
 
   $line = preg_replace('/([^\\\\])~/','\\1 ', $line);
 
-  $line = str_replace('---','—',$line);
-  $line = str_replace('--','–',$line);
+  $line = str_replace(array('---', '--'), array('—', '–'), $line);
 
-  $line = str_replace('``','"', $line);
-  $line = str_replace("''",'"', $line);
+  $line = str_replace(array('``', "''"), array('"', '"'), $line);
 
   // performance increases with this test
   // bug found by Serge Barral: what happens if we have curly braces only (typically to ensure case in Latex)