Added custom caching functions

This is a combination of 20 commits:
added cache callback #212

added test

Added text for custom cache

formating and tests

added caching_auto_clear option

moved custom cache test for php 5.3+

fixed ConfigTest.php

tabs to spaces

formating

formating

added `create_cache_key` callback option

added $table_name to clear cache function

added $table_name to _create_cache_key

added missing params

added $table_name to cache_query_result

formating

tabs

added $table_name to check_query_cache

unify cache parameters order

`table_name` is more important than `connection_name`

formating

1 files changed, 43 insertions, 0 deletions

diff --git a/docs/configuration.rst b/docs/configuration.rst
index dba0c8c..a93c91e 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -287,6 +287,21 @@ Idiorm can cache the queries it executes during a request. To enable
 query caching, set the ``caching`` option to ``true`` (it is ``false``
 by default).
 
+.. code-block:: php
+
+    <?php
+    ORM::configure('caching', true);
+    
+    
+Setting: ``caching_auto_clear``
+
+Idiorm's cache is never cleared by default. If you wish to automatically clear it on save, set ``caching_auto_clear`` to ``true``
+
+.. code-block:: php
+
+    <?php
+    ORM::configure('caching_auto_clear', true);
+
 When query caching is enabled, Idiorm will cache the results of every
 ``SELECT`` query it executes. If Idiorm encounters a query that has
 already been run, it will fetch the results directly from its cache and
@@ -313,6 +328,34 @@ Warnings and gotchas
    application, as all database rows that are fetched during each
    request are held in memory. If you are working with large quantities
    of data, you may wish to disable the cache.
+   
+If you wish to use custom caching functions, you can set them from the configure options. 
+
+.. code-block:: php
+
+    <?php
+        $my_cache = array();
+        ORM::configure('cache_query_result', function ($cache_key, $value, $table_name, $connection_name) use (&$my_cache) {
+            $my_cache[$cache_key] = $value;
+        });
+        ORM::configure('check_query_cache', function ($cache_key, $table_name, $connection_name) use (&$my_cache) {
+            if(isset($my_cache[$cache_key])){
+               return $my_cache[$cache_key];
+            } else {
+                return false;
+            }
+        });
+        ORM::configure('clear_cache', function ($table_name, $connection_name) use (&$my_cache) {
+             $my_cache = array();
+        });
+        
+        ORM::configure('create_cache_key', function ($query, $parameters, $table_name, $connection_name) {
+            $parameter_string = join(',', $parameters);
+            $key = $query . ':' . $parameter_string;
+            $my_key = 'my-prefix'.crc32($key);
+            return $my_key;
+        });
+
 
 .. _PDO documentation: http://php.net/manual/en/pdo.construct.php
 .. _the PDO documentation: http://www.php.net/manual/en/pdo.construct.php