Support non-template-namespace templates

[tacsipacsi]

In wikitext, page titles after {{ default to the template namespace, but can be overridden by explicitly specifying a namespace, or : to transclude a mainspace page. PetScan implements the first part – defaulting to the template namespace –, but not the second, the ability to override the namespace. Consequently, pages transcluded from other namespaces cannot be searched for using the textareas at Templates&links / Templates.

If I understand the code correctly, this is what happens when I input something in the Has all of these templates: field:

Input	Actual SQL fragment	Expected SQL fragment	Correct?
Title	lt_namespace=10 AND lt_title='Title'	lt_namespace=10 AND lt_title='Title'	Yes
Module:Title	lt_namespace=10 AND lt_title='Module:Title'	lt_namespace=828 AND lt_title='Title'	No
:Title	lt_namespace=10 AND lt_title=':Title'	lt_namespace=0 AND lt_title='Title'	No

The latter two should be fixed.

Reference: https://en.wikipedia.org/w/index.php?title=User_talk:Magnus_Manske&diff=1178068305