The simple pattern matches were conflicting in some situations. To make
this backwards compatable we need to convert it to a Regex pattern match
instead, and provide the quoted and unquoted variants.

There were two issues here:
* I am on the [categoryname] category page page (duplicated page)
* the wrong URL was being used

Since an incorrect URL was used I felt it safe to rename the step from
'category page page' to 'category page'.

This commit makes the following improvements to core page resolverss:
* allows for mixed case naming (course, Course, etc.)
* allows fields other than the idnumber to be specified:
** course: idnumber, shortname, fullname
** course category: idnumber, name

Whilst some of these fields are not unique, they will typically be
unique in most test scenarios. Where they are not then the idnumber
should be used in preference.