Don't always mark new instance as existing

Only mark new instance as existing if explicitly set.
This makes it posible to create a new object like this:
$foo = new Foo(array('bar'=>'bloo', 'baz'=>'foo'))
$foo->commit()
Add default_order
default_order is static
Throw exception if no primary key can be found
Only lookup id in join if no connection exists

This makes it possible to use join tables that lack primary id

Example:

Table: test1(id, data)
Table: test2(id, data)
Table: test1_test2_join(test1_id, test2_id) (both foreign keys)

Then run
Test1::count(array("test1_test2_join.test2.data"=>'foo'))
Before this fix that would give the error "no primary key in
test1_test2_join, but this commit fixes that.
Adds first and one-functions
Remove exception for primary key missing

Instead always make sure the array is at least empty

fix_join can accept one primary key to be null when trying to join
without foreign key connection.
Adds subclass that performs validations
Add uniquness validator
Add validation example
Add method for updating or creating from array

This method is best used with postdata. The same method can be used for
creating and updating an object. If id is set and not null the object
with the given id will be updated, otherwise a new object is created.
Adds support for cloning
Merge pull request #1 from p-blomberg/master

HTML_ACCESS as global variable instead of constant
Removing broken uniqueness validation
Actually use default_order
Merge branch 'master' of https://github.com/NitroXy/BasicObject
Add __toString
Add error handling to delete()
Change update_attributes to commit by default

I at least expect a method with that name to commit, but
since one migth need it to not do that it can be toggled
prevent errors in update_attributes with id

The problem occurs when you have a form that has an id-field that is
null if it is a new object, and otherwise update, and the id-field has
another name. Then bo tries to insert a column id, but it doesn't exist.
Unsetting it like this prevents the error.