Facility items 003 chemicals (reprise)

Using the discussion from https://github.com/CleverRaven/Cataclysm-DDA/pull/9215 I've put up a tiered system for chemicals and populated it with the first batch of chemicals and a nice bomb to keep things interesting.

In total, I am planning some 30 chemicals (15 out of the way already, 10 more shortly) and some 20 devices (among them: Thermite, RDX, HMTD, TCAP, Powder charge, Hexamine, Smoke curtain, Rocket Candy, Home-made rocket).

Please comment on what do You think of these ideas and tell me if there is something obvious, that I should add to the list.
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