Add Megacoin (MEC) support (#223)

defs/bitcoin/megacoin.json

@@ -0,0 +1,38 @@
+{
+  "coin_name": "Megacoin",
+  "coin_shortcut": "MEC",
+  "coin_label": "Megacoin",
+  "website": "https://www.megacoin.eu",
+  "github": "https://github.com/LIMXTEC/Megacoin",
+  "maintainer": "limxdev <contact@megacoin.eu>",
+  "curve_name": "secp256k1",
+  "address_type": 50,
+  "address_type_p2sh": 5,
+  "maxfee_kb": 1000000,
+  "minfee_kb": 1000,
+  "signed_message_header": "MegaCoin Signed Message:\n",
+  "hash_genesis_block": "7520788e2d99eec7cf6cf7315577e1268e177fff94cb0a7caf6a458ceeea9ac2",
+  "xprv_magic": 76066276,
+  "xpub_magic": 76067358,
+  "xpub_magic_segwit_p2sh": 77429938,
+  "xpub_magic_segwit_native": 78792518,
+  "bech32_prefix": null,
+  "cashaddr_prefix": null,
+  "slip44": 217,
+  "segwit": true,
+  "decred": false,
+  "fork_id": null,
+  "force_bip143": false,
+  "bip115": false,
+  "default_fee_b": {
+    "Low": 10
+  },
+  "dust_limit": 546,
+  "blocktime_seconds": 150,
+  "uri_prefix": "megacoin",
+  "min_address_length": 27,
+  "max_address_length": 34,
+  "bitcore": [],
+  "blockbook": [],
+  "cooldown": 100
+}