Multiple OR'ed conditions support

[lrlopez]

Multiple OR'ed conditions

You can add simple OR'ed conditions to the same WHERE clause using where_any_is. You should specify multiple conditions using an array of items. Each item will be an associative array that contains
a multiple conditions.

    <?php
    $people = ORM::for_table('person')
                ->where_any_is(array(
                    array('name' => 'Joe', 'age' => 10),
                    array('name' => 'Fred', 'age' => 20)))
                ->find_many();

    // Creates SQL:
    SELECT * FROM `widget` WHERE (( `name` = 'Joe' AND `age` = '10' ) OR
                                  ( `name` = 'Fred' AND `age` = '20' ));

By default, it uses the equal operator for every column, but it can be overriden for any column using a second parameter:

    <?php
    $people = ORM::for_table('person')
                ->where_any_is(array(
                    array('name' => 'Joe', 'age' => 10),
                    array('name' => 'Fred', 'age' => 20)), array('age' => '>'))
                ->find_many();

    // Creates SQL:
    SELECT * FROM `widget` WHERE (( `name` = 'Joe' AND `age` > '10' ) OR
                                  ( `name` = 'Fred' AND `age` > '20' ));

If you want to set the default operator for all the columns, just pass it as the second parameter:

    <?php
    $people = ORM::for_table('person')
                ->where_any_is(array(
                    array('score' => '5', 'age' => 10),
                    array('score' => '15', 'age' => 20)), '>')
                ->find_many();

    // Creates SQL:
    SELECT * FROM `widget` WHERE (( `score` > '5' AND `age` > '10' ) OR
                                  ( `score` > '15' AND `age` > '20' ));

[lrlopez]

I know about the Pareto Principle that inspires Idiorm & Paris, but I think the implementation is simple enough for the benefits that you get.

This PR is also needed to support where_id_in() (#202) when compound keys are used.

[periyasamy25]

How to write this query?
SELECT * FROM table WHERE (column1 LIKE '%value%' OR column2 LIKE '%value1%') AND column3='value3' order by column1 asc