Add Decred mainnet coin definition (#101)

defs/coins/decred.json

@@ -0,0 +1,38 @@
+{
+  "coin_name": "Decred",
+  "coin_shortcut": "DCR",
+  "coin_label": "Decred",
+  "website": "https://www.decred.org",
+  "github": "https://github.com/decred/dcrd",
+  "maintainer": "Alex Yocom-Piatt <ay-p@decred.org>",
+  "curve_name": "secp256k1_decred",
+  "address_type": 1855,
+  "address_type_p2sh": 1818,
+  "maxfee_kb": 1000000,
+  "minfee_kb": 10000,
+  "signed_message_header": "Decred Signed Message:\n",
+  "hash_genesis_block": "298e5cc3d985bfe7f81dc135f360abe089edd4396b86d2de66b0cef42b21d980",
+  "xprv_magic": 50177256,
+  "xpub_magic": 50178342,
+  "xpub_magic_segwit_p2sh": null,
+  "xpub_magic_segwit_native": null,
+  "bech32_prefix": null,
+  "cashaddr_prefix": null,
+  "slip44": 42,
+  "segwit": false,
+  "decred": true,
+  "forkid": null,
+  "force_bip143": false,
+  "default_fee_b": {
+    "Normal": 10
+  },
+  "dust_limit": 546,
+  "blocktime_seconds": 600,
+  "address_prefix": "bitcoin:",
+  "min_address_length": 35,
+  "max_address_length": 35,
+  "bitcore": [
+    "https://mainnet.decred.org"
+  ],
+  "blockbook": []
+}