Numerous documentation and test code fixes for HTML Purifier loading

- Improve documentation for stub files
- Synchronize stub files between extras/ and library/
- Remove unnecessary include in function file
- Remove special treatment of Bootstrap
- Improve docs for HTMLPurifier, converted singleton to use static member variables and removed reference
- Add HTMLPurifier.path.php stub file
- Update sample test settings
- Reorganize includes in test files

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1559 48356398-32a2-884e-a903-53898d9a118a

test-settings.sample.php

@@ -9,7 +9,11 @@
 set_time_limit(0);
 
 // Turning off output buffering will prevent mysterious errors from core dumps
-@ob_end_flush();
+$data = @ob_get_clean();
+if ($data !== false && $data !== '') {
+    echo "Output buffer contains data [".urlencode($data)."]\n";
+    exit;
+}
 
 // Where is SimpleTest located?
 $simpletest_location = '/path/to/simpletest/';
@@ -20,6 +24,9 @@ $csstidy_location    = '/path/to/csstidy/';
 // For tests/multitest.php, which versions to test?
 $versions_to_test    = array();
 
+// Stable PHP binary to use when invoking maintenance scripts.
+$php = 'php';
+
 // For tests/multitest.php, what is the multi-version executable? It must
 // accept an extra parameter (version number) before all other arguments
 $phpv = 'phpv';