Adds a system for printing stats to the disassembler

[ike709]

This adds a stats command to the disassembler which can be extended to provide various info about the bytecode. For now I've added a procs-by-type argument which prints the number of proc declarations on each type in descending order.

I've also spruced up the help command with the ability to take a command argument to learn more about a specific command.

Here's an excerpt from TG:

Counting all proc declarations by type. This may take a moment.
Type: Proc Declarations
<global>: 1595
/datum/controller/global_vars: 979
/client: 504
/mob/living: 441
/atom: 359
/mob: 328
/mob/living/carbon: 184
/atom/movable: 131
/obj/item: 128
/mob/living/carbon/human: 101