CAT and FEAT commands

One of the good things about doing some grammar development on SHRD2 is that it suggests ideas for new development environment functionality. I got tired of consulting the grammar every time I needed to find out what features a category had, or what possible values a feature could take. So I added a couple of new commands called CAT and FEAT, which give you those pieces of information. Here's an example:

>> CAT p
(Display information for specified category)

Features for category "p": [def,obj_sem_n_type,postposition,sem,sem_p_type,sem_pp_type]

--- Performed command CAT p, time = 0.00 seconds

>> FEAT sem_p_type         
(Display information for specified feature)

Feature values for feature "sem_p_type": [[back,down,none,normal,off,onoff,over,up,updown]]

--- Performed command FEAT sem_p_type, time = 0.00 seconds