Added support multiple operators and multiple conditions in query builder...

Better not to watch a comparison of Github, there's something difficult to disassemble. I try to explain the changes.

*_The main purpose of the changes is to support a variable number of input parameters_*

In which the code is embedded the new logic:

* in the method [\_compile_conditions()](https://github.com/KostyaTretyak/database/blob/954e64830a1960a018d354a39c4eb4085d62d503/classes/Kohana/Database/Query/Builder.php#L84-L128)
* added new method \_ condition_to_str(), but all of its code is taken from the method \_ compile_conditions(). Code in this method changed the form, not logic.
* added new method [\_quote_value()](https://github.com/KostyaTretyak/database/blob/caf7de40112b750793344e2f1ac8da6d8ac90d96/classes/Kohana/Database/Query/Builder.php#L147-L155), but all of its code is taken from [part](https://github.com/kohana/database/blob/cb64b293587309358207b0e17025b55eb902c563/classes/Kohana/Database/Query/Builder.php#L113-L117) method \_ compile_conditions().

What conditions you can write for the new builder:

~~~
$obj_Database_Query_Builder_Select =
    DB::select()
//	->or_where('number', array('<','>'), array(10, 50))
//	Note: arrays are of equal length.
//	Will output:
//	 `number` < 10
//	OR `number` > 50

//	->or_where('name', array('=', 'like'), array('Peter', 'Ko%', 'Geo%'))
//	Note: arrays are of unequal length
//	Will output:
//	`name` = 'Peter'
//	OR `name` LIKE 'Ko%'
//	OR `name` LIKE 'Geo%'

//	->or_where('number', array('>=', '<'), array(10))
//	Note: arrays are of unequal length
//	Will output:
//	`number` >= 10 (because there is no sense output `number` >= 10 OR `number` < 10)

//	->and_where('number', array('>=', '<'), array(10))
//	Note: arrays are of unequal length
//	Will output:
//	`number` >= 10 (because there is no sense output `number` >= 10 AND `number` < 10)

//	->and_where('name', array('like'), array('_____a', 'Ko%'))
//	Note: arrays are of unequal length, and usage and_where()
//	Will output:
//	`name` LIKE '_____a'
//	AND `name` LIKE 'Ko%'

//	->or_where('number', array('in'), array(10, 50))
//	Note: arrays are of unequal length, and usage single operator IN
//	Will output:
//	`number` IN (10, 50)

//	->or_where('number', array('in', '>', '<'), array(array(10, 50), 60, 2))
//	Note: usage operator IN
//	Will output:
//	`number` IN (10, 50)
//	OR `number` > 60
//	OR `number` < 2
;

echo Debug::vars((string) $obj_Database_Query_Builder_Select);
~~~

Of course comments need to rewrite to make it more properly in English.

P.S. For testing, you can add yourself [this file](https://gist.github.com/KostyaTretyak/8533876) in APPPATH/classes/Database/Query/Builder.php