mechanic: move word lists to data files

The word lists (monsters, spells, equipment, races, classes, titles and
so on) now live in pqcli/data/*.json instead of pqcli/config.py. A
GameData object loaded at startup is passed to the simulation and UIs.

Users can replace any list by putting NAME.json in
$XDG_CONFIG_HOME/pqcli/data/ or a directory given with --data-dir.
--dump-data DIR copies the built-in files out for editing. Malformed
files are reported and pqcli exits before starting the UI.

Combat task descriptions come from the new combat_verbs list, with
{target} standing for the enemy. The built-in list holds only "Executing
{target}", and a single verb consumes no random roll, so stock gameplay
is unchanged. Recorded traces in tests/fixtures pin this down.

Monster, Race and Class stay in pqcli.config so existing saves still
load.

Resolves #3

pqcli/data/classes.json

@@ -0,0 +1,20 @@
+[
+  {"name": "Ur-Paladin", "attr": ["WIS", "CON"]},
+  {"name": "Voodoo Princess", "attr": ["INT", "CHA"]},
+  {"name": "Robot Monk", "attr": ["STR"]},
+  {"name": "Mu-Fu Monk", "attr": ["DEX"]},
+  {"name": "Mage Illusioner", "attr": ["INT", "MP Max"]},
+  {"name": "Shiv-Knight", "attr": ["DEX"]},
+  {"name": "Inner Mason", "attr": ["CON"]},
+  {"name": "Fighter/Organist", "attr": ["CHA", "STR"]},
+  {"name": "Puma Burgular", "attr": ["DEX"]},
+  {"name": "Runeloremaster", "attr": ["WIS"]},
+  {"name": "Hunter Strangler", "attr": ["DEX", "INT"]},
+  {"name": "Battle-Felon", "attr": ["STR"]},
+  {"name": "Tickle-Mimic", "attr": ["WIS", "INT"]},
+  {"name": "Slow Poisoner", "attr": ["CON"]},
+  {"name": "Bastard Lunatic", "attr": ["CON"]},
+  {"name": "Lowling", "attr": ["WIS"]},
+  {"name": "Birdrider", "attr": ["WIS"]},
+  {"name": "Vermineer", "attr": ["INT"]}
+]