[HPFGU-Catalogue] Subject category list - version 2

[silmariel]

> Presumably all the sections of this list should be numbered to
> several levels, eg
>
> 1
> 1.1
> 1.1.1
> 1.1.1
>
> This is ok, but the characters are currently organised
> alphabetically, what happens if we insert a new character half way
> down a list ??


Sorry for a brief response, I've slept only 2-3 hours and I'm melting down.

I expected it would be done, the categories table of the database is made to 
allow that, that's why we have 3 different numbers to control the category: 
Category_ID,  Number,   father_ID. Number is the position expected for that 
subcategory (an integer), so in case we decide that main category 2 is now 3 
actually how the posts are inserted into categories in the database won't 
change, it will change the Number. It should be called something as 
IsChildNumber.

Posts can also be inserted at any level, not only the lower.  

Carolina