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/boring_items.json

@@ -0,0 +1,44 @@
+[
+  "nail",
+  "lunchpail",
+  "sock",
+  "I.O.U.",
+  "cookie",
+  "pint",
+  "toothpick",
+  "writ",
+  "newspaper",
+  "letter",
+  "plank",
+  "hat",
+  "egg",
+  "coin",
+  "needle",
+  "bucket",
+  "ladder",
+  "chicken",
+  "twig",
+  "dirtclod",
+  "counterpane",
+  "vest",
+  "teratoma",
+  "bunny",
+  "rock",
+  "pole",
+  "carrot",
+  "canoe",
+  "inkwell",
+  "hoe",
+  "bandage",
+  "trowel",
+  "towel",
+  "planter box",
+  "anvil",
+  "axle",
+  "tuppence",
+  "casket",
+  "nosegay",
+  "trinket",
+  "credenza",
+  "writ"
+]